diff --git a/admin/code/GroupImportForm.php b/admin/code/GroupImportForm.php
index c084aeecc..850fe7e75 100644
--- a/admin/code/GroupImportForm.php
+++ b/admin/code/GroupImportForm.php
@@ -70,17 +70,17 @@ class GroupImportForm extends Form {
 		
 		// result message
 		$msgArr = array();
-		if($result->CreatedCount()) $msgArr[] = sprintf(
-			_t('GroupImportForm.ResultCreated', 'Created %d groups'),
-			$result->CreatedCount()
+		if($result->CreatedCount()) $msgArr[] = _t(
+			'GroupImportForm.ResultCreated', 'Created {count} groups',
+			array('count' => $result->CreatedCount())
 		);
-		if($result->UpdatedCount()) $msgArr[] = sprintf(
-			_t('GroupImportForm.ResultUpdated', 'Updated %d groups'),
-			$result->UpdatedCount()
+		if($result->UpdatedCount()) $msgArr[] = _t(
+			'GroupImportForm.ResultUpdated', 'Updated %d groups',
+			array('count' => $result->UpdatedCount())
 		);
-		if($result->DeletedCount()) $msgArr[] = sprintf(
-			_t('GroupImportForm.ResultDeleted', 'Deleted %d groups'),
-			$result->DeletedCount()
+		if($result->DeletedCount()) $msgArr[] = _t(
+			'GroupImportForm.ResultDeleted', 'Deleted %d groups',
+			array('count' => $result->DeletedCount())
 		);
 		$msg = ($msgArr) ? implode(',', $msgArr) : _t('MemberImportForm.ResultNone', 'No changes');
 	
diff --git a/admin/code/LeftAndMain.php b/admin/code/LeftAndMain.php
index e0ec7e4d4..a394f5fc1 100644
--- a/admin/code/LeftAndMain.php
+++ b/admin/code/LeftAndMain.php
@@ -1299,12 +1299,12 @@ class LeftAndMain extends Controller implements PermissionProvider {
 
 			$title = _t("{$class}.MENUTITLE", LeftAndMain::menu_title_for_class($class));
 			$perms["CMS_ACCESS_" . $class] = array(
-				'name' => sprintf(_t(
+				'name' => _t(
 					'CMSMain.ACCESS', 
-					"Access to '%s' section",
-					
-					"Item in permission selection identifying the admin section. Example: Access to 'Files & Images'"
-				), $title, null),
+					"Access to '{title}' section",
+					"Item in permission selection identifying the admin section. Example: Access to 'Files & Images'",
+					array('title' => $title)
+				),
 				'category' => _t('Permission.CMS_ACCESS_CATEGORY', 'CMS Access')
 			);
 		}
diff --git a/admin/code/MemberImportForm.php b/admin/code/MemberImportForm.php
index 1b15692ea..bb6274738 100644
--- a/admin/code/MemberImportForm.php
+++ b/admin/code/MemberImportForm.php
@@ -75,17 +75,17 @@ class MemberImportForm extends Form {
 		
 		// result message
 		$msgArr = array();
-		if($result->CreatedCount()) $msgArr[] = sprintf(
-			_t('MemberImportForm.ResultCreated', 'Created %d members'),
-			$result->CreatedCount()
+		if($result->CreatedCount()) $msgArr[] = _t(
+			'MemberImportForm.ResultCreated', 'Created {count} members',
+			array('count' => $result->CreatedCount())
 		);
-		if($result->UpdatedCount()) $msgArr[] = sprintf(
-			_t('MemberImportForm.ResultUpdated', 'Updated %d members'),
-			$result->UpdatedCount()
+		if($result->UpdatedCount()) $msgArr[] = _t(
+			'MemberImportForm.ResultUpdated', 'Updated {count} members',
+			array('count' => $result->UpdatedCount())
 		);
-		if($result->DeletedCount()) $msgArr[] = sprintf(
-			_t('MemberImportForm.ResultDeleted', 'Deleted %d members'),
-			$result->DeletedCount()
+		if($result->DeletedCount()) $msgArr[] = _t(
+			'MemberImportForm.ResultDeleted', 'Deleted %d members',
+			array('count' => $result->DeletedCount())
 		);
 		$msg = ($msgArr) ? implode(',', $msgArr) : _t('MemberImportForm.ResultNone', 'No changes');
 	
diff --git a/admin/code/ModelAdmin.php b/admin/code/ModelAdmin.php
index d55a3f1e4..e19dfbbc4 100644
--- a/admin/code/ModelAdmin.php
+++ b/admin/code/ModelAdmin.php
@@ -387,17 +387,17 @@ abstract class ModelAdmin extends LeftAndMain {
 		$results = $loader->load($_FILES['_CsvFile']['tmp_name']);
 
 		$message = '';
-		if($results->CreatedCount()) $message .= sprintf(
-			_t('ModelAdmin.IMPORTEDRECORDS', "Imported %s records."),
-			$results->CreatedCount()
+		if($results->CreatedCount()) $message .= _t(
+			'ModelAdmin.IMPORTEDRECORDS', "Imported {count} records.",
+			array('count' => $results->CreatedCount())
 		);
-		if($results->UpdatedCount()) $message .= sprintf(
-			_t('ModelAdmin.UPDATEDRECORDS', "Updated %s records."),
-			$results->UpdatedCount()
+		if($results->UpdatedCount()) $message .= _t(
+			'ModelAdmin.UPDATEDRECORDS', "Updated {count} records.",
+			array('count' => $results->UpdatedCount())
 		);
-		if($results->DeletedCount()) $message .= sprintf(
-			_t('ModelAdmin.DELETEDRECORDS', "Deleted %s records."),
-			$results->DeletedCount()
+		if($results->DeletedCount()) $message .= _t(
+			'ModelAdmin.DELETEDRECORDS', "Deleted {count} records.",
+			array('count' => $results->DeletedCount())
 		);
 		if(!$results->CreatedCount() && !$results->UpdatedCount()) $message .= _t('ModelAdmin.NOIMPORT', "Nothing to import");
 
diff --git a/admin/code/SecurityAdmin.php b/admin/code/SecurityAdmin.php
index 4e0690d90..c43d4d798 100755
--- a/admin/code/SecurityAdmin.php
+++ b/admin/code/SecurityAdmin.php
@@ -219,7 +219,7 @@ class SecurityAdmin extends LeftAndMain implements PermissionProvider {
 		$title = _t("SecurityAdmin.MENUTITLE", LeftAndMain::menu_title_for_class($this->class));
 		return array(
 			"CMS_ACCESS_SecurityAdmin" => array(
-				'name' => sprintf(_t('CMSMain.ACCESS', "Access to '%s' section"), $title),
+				'name' => _t('CMSMain.ACCESS', "Access to '{title}' section", array('title' => $title)),
 				'category' => _t('Permission.CMS_ACCESS_CATEGORY', 'CMS Access'),
 				'help' => _t(
 					'SecurityAdmin.ACCESS_HELP',
diff --git a/core/Core.php b/core/Core.php
index a340abeff..d2e25d102 100644
--- a/core/Core.php
+++ b/core/Core.php
@@ -386,8 +386,8 @@ function stripslashes_recursively(&$array) {
 /**
  * @see i18n::_t()
  */
-function _t($entity, $string = "", $context = "") {
-	return i18n::_t($entity, $string, $context);
+function _t($entity, $string = "", $context = "", $injection = "") {
+	return i18n::_t($entity, $string, $context, $injection);
 }
 
 /**
diff --git a/docs/en/changelogs/3.0.0.md b/docs/en/changelogs/3.0.0.md
index 3757dbc93..63c9b1fac 100644
--- a/docs/en/changelogs/3.0.0.md
+++ b/docs/en/changelogs/3.0.0.md
@@ -455,13 +455,36 @@ and was rarely used in practice - so we moved it to a "[homepagefordomain](https
 
 ### New syntax for translatable _t functions [i18n-t]###
 
-You can now call the _t() function in both templates and code with a namespace and string to translate, as well as a
-comment and injection array. Note that the proxity arguement to _t is no longer supported.
+You can now call the `_t()` function in both templates and code with a namespace and string to translate, as well as a comment and injection array. 
 
 The new syntax supports injecting variables into the translation. For example:
 
 	:::php
-    _t('i18nTestModule.INJECTIONS2', "Hello {name} {greeting}", array("name"=>"Paul", "greeting"=>"good you are here"));
+    _t(
+    	'i18nTestModule.INJECTIONS2', 
+    	"Hello {name} {greeting}", 
+    	array("name"=>"Paul", "greeting"=>"good you are here")
+    );
+
+We've written the injection logic in a way that keeps backwards compatible with
+existing translations. This means that you can migrate from `sprintf()` to the new injection
+API incrementally. The following to "mixed usage" examples still work, although they
+don't get the advantage of flexible ordering in substitutions.
+
+	:::php
+	_t(
+		'i18nTestModule.INJECTIONS2', 
+		"Hello {name} {greeting}", 
+		array("Paul", "good you are here")
+	);
+	_t(
+		'i18nTestModule.INJECTIONS2', 
+		"Hello %s, %s", 
+		array("name"=>"Paul", "greeting"=>"good you are here")
+	);
+
+Of course, you can keep using `sprintf()` for variable substitution in your own code.
+
 
 ### Default translation source in YML instead of PHP $lang array, using Zend_Translate {#zend-translate}
 
diff --git a/docs/en/topics/i18n.md b/docs/en/topics/i18n.md
index ab16c430c..fd61ff134 100644
--- a/docs/en/topics/i18n.md
+++ b/docs/en/topics/i18n.md
@@ -180,9 +180,10 @@ Therefore, the following would be a valid use in templates:
 
 Using SS templating variables in the translatable string (e.g. $Author, $Date..) is not currently supported.
 
-### Injection-support
+### Injection Support
 
-Variable injection in _t allows us to dynamically replace parts of a translated string, e.g. by a username or a page-title.
+Variable injection in `_t()` allows us to dynamically replace parts of a translated string, e.g. by a username or a page-title. The named parameters also allow flexible ordering of placeholders,
+which might vary depending on the used language.
 
 	:::php
 	// in PHP-file
@@ -196,6 +197,10 @@ Variable injection in _t allows us to dynamically replace parts of a translated
 	// in SS-template ($Name must be available in the current template-scope)
 	<%t MYPROJECT.INJECTIONS "Hello {name} {greeting}" name="$Name" greeting="good to see you" %>
 
+Note that you can still use `sprintf()` wrapped around a `_t()` call
+for your substitutions. In contrast to `sprintf()`, our API has a more translator friendly
+placeholder syntax, as well as more graceful fallback if not all placeholders are found
+(an outdated translation with less placeholders will throw a notice rather than a fatal error).
 
 ## Collecting text
 
diff --git a/filesystem/Upload.php b/filesystem/Upload.php
index 31339dcec..7af603fb2 100644
--- a/filesystem/Upload.php
+++ b/filesystem/Upload.php
@@ -496,28 +496,22 @@ class Upload_Validator {
 		if(!$this->isValidSize()) {
 			$ext = (isset($pathInfo['extension'])) ? $pathInfo['extension'] : '';
 			$arg = File::format_size($this->getAllowedMaxFileSize($ext));
-			$this->errors[] = sprintf(
-				_t(
-					'File.TOOLARGE', 
-					'Filesize is too large, maximum %s allowed.',
-					
-					'Argument 1: Filesize (e.g. 1MB)'
-				),
-				$arg
+			$this->errors[] = _t(
+				'File.TOOLARGE', 
+				'Filesize is too large, maximum {size} allowed.',
+				'Argument 1: Filesize (e.g. 1MB)',
+				array('size' => $arg)
 			);
 			return false;
 		}
 
 		// extension validation
 		if(!$this->isValidExtension()) {
-			$this->errors[] = sprintf(
-				_t(
-					'File.INVALIDEXTENSION', 
-					'Extension is not allowed (valid: %s)',
-					
-					'Argument 1: Comma-separated list of valid extensions'
-				),
-				wordwrap(implode(', ', $this->allowedExtensions))
+			$this->errors[] = _t(
+				'File.INVALIDEXTENSION', 
+				'Extension is not allowed (valid: {extensions})',
+				'Argument 1: Comma-separated list of valid extensions',
+				array('extensions' => wordwrap(implode(', ', $this->allowedExtensions)))
 			);
 			return false;
 		}
diff --git a/forms/ComplexTableField.php b/forms/ComplexTableField.php
index ddb6d112f..ec04fd7aa 100644
--- a/forms/ComplexTableField.php
+++ b/forms/ComplexTableField.php
@@ -485,12 +485,11 @@ JS;
 		
 		$editLink = Controller::join_links($this->Link(), 'item/' . $childData->ID . '/edit');
 		
-		$message = sprintf(
-			_t('ComplexTableField.SUCCESSADD', 'Added %s %s %s'),
-			$childData->singular_name(),
-			'<a href="' . $editLink . '">' . $childData->Title . '</a>',
-			$closeLink
+		$message = _t(
+			'ComplexTableField.SUCCESSADD2', 'Added {name}',
+			array('name' => $childData->singular_name())
 		);
+		$message .= '<a href="' . $editLink . '">' . $childData->Title . '</a>' . $closeLink;
 		
 		$form->sessionMessage($message, 'good');
 		
diff --git a/forms/ConfirmedPasswordField.php b/forms/ConfirmedPasswordField.php
index 889b3342a..213150b8b 100644
--- a/forms/ConfirmedPasswordField.php
+++ b/forms/ConfirmedPasswordField.php
@@ -247,13 +247,25 @@ class ConfirmedPasswordField extends FormField {
 		if(($this->minLength || $this->maxLength)) {
 			if($this->minLength && $this->maxLength) {
 				$limit = "{{$this->minLength},{$this->maxLength}}";
-				$errorMsg = sprintf(_t('ConfirmedPasswordField.BETWEEN', 'Passwords must be %s to %s characters long.'), $this->minLength, $this->maxLength);
+				$errorMsg = _t(
+					'ConfirmedPasswordField.BETWEEN', 
+					'Passwords must be {min} to {max} characters long.', 
+					array('min' => $this->minLength, 'max' => $this->maxLength)
+				);
 			} elseif($this->minLength) {
 				$limit = "{{$this->minLength}}.*";
-				$errorMsg = sprintf(_t('ConfirmedPasswordField.ATLEAST', 'Passwords must be at least %s characters long.'), $this->minLength);
+				$errorMsg = _t(
+					'ConfirmedPasswordField.ATLEAST', 
+					'Passwords must be at least {min} characters long.', 
+					array('min' => $this->minLength)
+				);
 			} elseif($this->maxLength) {
 				$limit = "{0,{$this->maxLength}}";
-				$errorMsg = sprintf(_t('ConfirmedPasswordField.MAXIMUM', 'Passwords must be at most %s characters long.'), $this->maxLength);
+				$errorMsg = _t(
+					'ConfirmedPasswordField.MAXIMUM', 
+					'Passwords must be at most {max} characters long.', 
+					array('max' => $this->maxLength)
+				);
 			}
 			$limitRegex = '/^.' . $limit . '$/';
 			if(!empty($value) && !preg_match($limitRegex,$value)) {
diff --git a/forms/CreditCardField.php b/forms/CreditCardField.php
index bcf246095..e8f8e83ed 100644
--- a/forms/CreditCardField.php
+++ b/forms/CreditCardField.php
@@ -51,9 +51,10 @@ class CreditCardField extends TextField {
 				}
 				$validator->validationError(
 					$this->name,
-					sprintf(
-						_t('Form.VALIDATIONCREDITNUMBER', "Please ensure you have entered the %s credit card number correctly."),
-						$number
+					_t(
+						'Form.VALIDATIONCREDITNUMBER', 
+						"Please ensure you have entered the {number} credit card number correctly.",
+						array('number' => $number)
 					),
 					"validation",
 					false
diff --git a/forms/DateField.php b/forms/DateField.php
index b352c6c2c..4d609abf9 100644
--- a/forms/DateField.php
+++ b/forms/DateField.php
@@ -310,9 +310,9 @@ class DateField extends TextField {
 		if(!$valid) {
 			$validator->validationError(
 				$this->name, 
-				sprintf(
-					_t('DateField.VALIDDATEFORMAT2', "Please enter a valid date format (%s)."), 
-					$this->getConfig('dateformat')
+				_t(
+					'DateField.VALIDDATEFORMAT2', "Please enter a valid date format ({format}).", 
+					array('format' => $this->getConfig('dateformat'))
 				), 
 				"validation", 
 				false
@@ -331,9 +331,9 @@ class DateField extends TextField {
 			if(!$this->valueObj->isLater($minDate) && !$this->valueObj->equals($minDate)) {
 				$validator->validationError(
 					$this->name, 
-					sprintf(
-						_t('DateField.VALIDDATEMINDATE', "Your date has to be newer or matching the minimum allowed date (%s)"), 
-						$minDate->toString($this->getConfig('dateformat'))
+					_t(
+						'DateField.VALIDDATEMINDATE', "Your date has to be newer or matching the minimum allowed date ({date})", 
+						array('date' => $minDate->toString($this->getConfig('dateformat')))
 					),
 					"validation", 
 					false
@@ -351,9 +351,9 @@ class DateField extends TextField {
 			if(!$this->valueObj->isEarlier($maxDate) && !$this->valueObj->equals($maxDate)) {
 				$validator->validationError(
 					$this->name, 
-					sprintf(
-						_t('DateField.VALIDDATEMAXDATE', "Your date has to be older or matching the maximum allowed date (%s)"), 
-						$maxDate->toString($this->getConfig('dateformat'))
+					_t(
+						'DateField.VALIDDATEMAXDATE', "Your date has to be older or matching the maximum allowed date ({date})", 
+						array('date' => $maxDate->toString($this->getConfig('dateformat')))
 					),
 					"validation", 
 					false
diff --git a/forms/FileIFrameField.php b/forms/FileIFrameField.php
index a5b651352..cbf469dec 100644
--- a/forms/FileIFrameField.php
+++ b/forms/FileIFrameField.php
@@ -92,9 +92,11 @@ class FileIFrameField extends FileField {
 				)
 			);
 		} else {
-			return sprintf(_t (
-				'FileIFrameField.ATTACHONCESAVED', '%ss can be attached once you have saved the record for the first time.'
-			), $this->FileTypeName());
+			return _t(
+				'FileIFrameField.ATTACHONCESAVED', 
+				'{type}s can be attached once you have saved the record for the first time.',
+				array('type' => $this->FileTypeName())
+			);
 		}
 	}
 	
@@ -130,9 +132,9 @@ class FileIFrameField extends FileField {
 		$selectFile = _t('FileIFrameField.FROMFILESTORE', 'From the File Store');
 		
 		if($this->AttachedFile() && $this->AttachedFile()->ID) {
-			$title = sprintf(_t('FileIFrameField.REPLACE', 'Replace %s'), $this->FileTypeName());
+			$title = _t('FileIFrameField.REPLACE', 'Replace {type}', array('type' => $this->FileTypeName()));
 		} else {
-			$title = sprintf(_t('FileIFrameField.ATTACH', 'Attach %s'), $this->FileTypeName());
+			$title = _t('FileIFrameField.ATTACH', 'Attach {type}', array('type' => $this->FileTypeName()));
 		}
 		
 		$fileSources = array();
@@ -235,7 +237,7 @@ class FileIFrameField extends FileField {
 			),
 			new FieldList (
 				$deleteButton = new FormAction (
-					'delete', sprintf(_t('FileIFrameField.DELETE', 'Delete %s'), $this->FileTypeName())
+					'delete', _t('FileIFrameField.DELETE', 'Delete {type}', array('type' => $this->FileTypeName()))
 				)
 			)
 		);
diff --git a/forms/NumericField.php b/forms/NumericField.php
index 872d9cbdf..218d777d4 100644
--- a/forms/NumericField.php
+++ b/forms/NumericField.php
@@ -16,9 +16,9 @@ class NumericField extends TextField{
 		if($this->value && !is_numeric(trim($this->value))){
  			$validator->validationError(
  				$this->name,
-				sprintf(
-					_t('NumericField.VALIDATION', "'%s' is not a number, only numbers can be accepted for this field"),
-					$this->value
+				_t(
+					'NumericField.VALIDATION', "'{value}' is not a number, only numbers can be accepted for this field",
+					array('value' => $this->value)
 				),
 				"validation"
 			);
diff --git a/forms/TimeField.php b/forms/TimeField.php
index 38b096d4a..330223793 100644
--- a/forms/TimeField.php
+++ b/forms/TimeField.php
@@ -143,9 +143,9 @@ class TimeField extends TextField {
 		if(!Zend_Date::isDate($this->value, $this->getConfig('timeformat'), $this->locale)) {
 			$validator->validationError(
 				$this->name, 
-				sprintf(
-					_t('TimeField.VALIDATEFORMAT', "Please enter a valid time format (%s)"), 
-					$this->getConfig('timeformat')
+				_t(
+					'TimeField.VALIDATEFORMAT', "Please enter a valid time format ({format})", 
+					array('format' => $this->getConfig('timeformat'))
 				), 
 				"validation", 
 				false
diff --git a/forms/UploadField.php b/forms/UploadField.php
index e23f89944..e8dcd4aca 100644
--- a/forms/UploadField.php
+++ b/forms/UploadField.php
@@ -348,23 +348,26 @@ class UploadField extends FileField {
 		if (count($this->getValidator()->getAllowedExtensions())) {
 			$allowedExtensions = $this->getValidator()->getAllowedExtensions();
 			$config['acceptFileTypes'] = '(\.|\/)(' . implode('|', $allowedExtensions) . ')$';
-			$config['errorMessages']['acceptFileTypes'] = sprintf(_t(
+			$config['errorMessages']['acceptFileTypes'] = _t(
 				'File.INVALIDEXTENSION', 
-				'Extension is not allowed (valid: %s)'
-			), wordwrap(implode(', ', $allowedExtensions)));
+				'Extension is not allowed (valid: {extensions})',
+				array('extensions' => wordwrap(implode(', ', $allowedExtensions)))
+			);
 		}
 		if ($this->getValidator()->getAllowedMaxFileSize()) {
 			$config['maxFileSize'] = $this->getValidator()->getAllowedMaxFileSize();
-			$config['errorMessages']['maxFileSize'] = sprintf(_t(
+			$config['errorMessages']['maxFileSize'] = _t(
 				'File.TOOLARGE', 
-				'Filesize is too large, maximum %s allowed.'
-			), File::format_size($config['maxFileSize']));
+				'Filesize is too large, maximum {size} allowed.',
+				array('size' => File::format_size($config['maxFileSize']))
+			);
 		}
 		if ($config['maxNumberOfFiles'] > 1) {
-			$config['errorMessages']['maxNumberOfFiles'] = sprintf(_t(
+			$config['errorMessages']['maxNumberOfFiles'] = _t(
 				'UploadField.MAXNUMBEROFFILES', 
-				'Max number of %s file(s) exceeded.'
-			), $config['maxNumberOfFiles']);
+				'Max number of {count} file(s) exceeded.',
+				array('count' => $config['maxNumberOfFiles'])
+			);
 		}
 		$configOverwrite = array();
 		if (is_numeric($config['maxNumberOfFiles']) && $this->getItems()->count()) {
@@ -459,10 +462,11 @@ class UploadField extends FileField {
 			// Report the constraint violation.
 			if ($tooManyFiles) {
 				if(!$this->getConfig('allowedMaxFileNumber')) $this->setConfig('allowedMaxFileNumber', 1);
-				$return['error'] = sprintf(_t(
+				$return['error'] = _t(
 					'UploadField.MAXNUMBEROFFILES', 
-					'Max number of %s file(s) exceeded.'
-				), $this->getConfig('allowedMaxFileNumber'));
+					'Max number of {count} file(s) exceeded.',
+					array('count' => $this->getConfig('allowedMaxFileNumber'))
+				);
 			}
 		}
 
diff --git a/forms/gridfield/GridFieldAddExistingAutocompleter.php b/forms/gridfield/GridFieldAddExistingAutocompleter.php
index a9f1f4629..1f4cfe036 100755
--- a/forms/gridfield/GridFieldAddExistingAutocompleter.php
+++ b/forms/gridfield/GridFieldAddExistingAutocompleter.php
@@ -251,15 +251,15 @@ class GridFieldAddExistingAutocompleter implements GridField_HTMLProvider, GridF
 				if($label) $labels[] = $label;
 			}
 			if($labels) {
-				return sprintf(
-					_t('GridField.PlaceHolderWithLabels', 'Find %s by %s', 'Find <object type> by <field names>'), 
-					singleton($dataClass)->plural_name(),
-					implode(', ', $labels)
+				return _t(
+					'GridField.PlaceHolderWithLabels', 
+					'Find {type} by {name}',  
+					array('type' => singleton($dataClass)->plural_name(), 'name' => implode(', ', $labels))
 				);
 			} else {
-				return sprintf(
-					_t('GridField.PlaceHolder', 'Find %s', 'Find <object type>'), 
-					singleton($dataClass)->plural_name()
+				return _t(
+					'GridField.PlaceHolder', 'Find {type}',
+					array('type' => singleton($dataClass)->plural_name())
 				);
 			}
 		}
diff --git a/i18n/i18n.php b/i18n/i18n.php
index 4e8460a06..c350797f6 100644
--- a/i18n/i18n.php
+++ b/i18n/i18n.php
@@ -1488,7 +1488,7 @@ class i18n extends Object implements TemplateGlobalProvider {
 		$translatorsByPrio = self::$translators;
 		if(!$translatorsByPrio) $translatorsByPrio = self::get_translators();
 
-		$returnValue = $string; // Fall back to default string argument
+		$returnValue = (is_string($string)) ? $string : ''; // Fall back to default string argument
 
 		foreach($translatorsByPrio as $priority => $translators) {
 			foreach($translators as $name => $translator) {
@@ -1512,9 +1512,36 @@ class i18n extends Object implements TemplateGlobalProvider {
 		}
 
 		// inject the variables from injectionArray (if present)
-		if ($injectionArray && count($injectionArray) > 0) {
-			foreach($injectionArray as $variable => $injection) {
-				$returnValue = str_replace('{'.$variable.'}', $injection, $returnValue);
+		if($injectionArray) {
+			$regex = '/\{[\w\d]*\}/i';
+			if(!preg_match($regex, $returnValue)) {
+				// Legacy mode: If no injection placeholders are found, 
+				// replace sprintf placeholders in fixed order.
+				$returnValue = vsprintf($returnValue, array_values($injectionArray));
+			} else if(!ArrayLib::is_associative($injectionArray)) {
+				// Legacy mode: If injection placeholders are found,
+				// but parameters are passed without names, replace them in fixed order.
+				$returnValue = preg_replace_callback(
+					$regex, 
+					function($matches) use(&$injectionArray) {
+						return $injectionArray ? array_shift($injectionArray) : '';
+					},
+					$returnValue
+				);
+			} else {
+				// Standard placeholder replacement with named injections and variable order.
+				foreach($injectionArray as $variable => $injection) {
+					$placeholder = '{'.$variable.'}';
+					$returnValue = str_replace($placeholder, $injection, $returnValue, $count);
+					if(!$count) {
+						SS_Log::log(sprintf(
+							"Couldn't find placeholder '%s' in translation string '%s' (id: '%s')",
+							$placeholder,
+							$returnValue,
+							$entity
+						), SS_Log::NOTICE);
+					}
+				}
 			}
 		}
 
diff --git a/i18n/i18nTextCollector.php b/i18n/i18nTextCollector.php
index d4a054523..fb5503830 100644
--- a/i18n/i18nTextCollector.php
+++ b/i18n/i18nTextCollector.php
@@ -162,6 +162,7 @@ class i18nTextCollector extends Object {
 		//Debug::message("Processing Module '{$module}'", false);
 
 		// Search for calls in code files if these exists
+		$fileList = array();
 		if(is_dir("$this->basePath/$module/code")) {
 			$fileList = $this->getFilesRecursive("$this->basePath/$module/code");
 		} else if($module == FRAMEWORK_DIR || substr($module, 0, 7) == 'themes/') {
diff --git a/lang/en.yml b/lang/en.yml
index 24a67903f..751121af7 100644
--- a/lang/en.yml
+++ b/lang/en.yml
@@ -55,7 +55,7 @@ en:
     NO: No
     YES: Yes
   CMSMain:
-    ACCESS: 'Access to ''%s'' section'
+    ACCESS: 'Access to ''{title}'' section'
     ACCESSALLINTERFACES: 'Access to all CMS sections'
     ACCESSALLINTERFACESHELP: 'Overrules more specific access settings.'
     SAVE: Save
@@ -72,7 +72,7 @@ en:
     YES: Yes
   ComplexTableField:
     CLOSEPOPUP: 'Close Popup'
-    SUCCESSADD: 'Added %s %s %s'
+    SUCCESSADD2: 'Added {name}'
     SUCCESSEDIT: 'Saved %s %s %s'
     SUCCESSEDIT2: 'Deleted %s %s'
   ComplexTableField.ss:
@@ -83,9 +83,9 @@ en:
     NEXT: Next
     PREVIOUS: Previous
   ConfirmedPasswordField:
-    ATLEAST: 'Passwords must be at least %s characters long.'
-    BETWEEN: 'Passwords must be %s to %s characters long.'
-    MAXIMUM: 'Passwords must be at most %s characters long.'
+    ATLEAST: 'Passwords must be at least {min} characters long.'
+    BETWEEN: 'Passwords must be {min} to {max} characters long.'
+    MAXIMUM: 'Passwords must be at most {max} characters long.'
     SHOWONCLICKTITLE: 'Change Password'
   CreditCardField:
     FIRST: first
@@ -108,16 +108,16 @@ en:
     MONTHS: ' months'
     SEC: ' sec'
     SECS: ' secs'
-    TIMEDIFFAGO: '%s ago'
-    TIMEDIFFIN: 'in %s'
+    TIMEDIFFAGO: '{difference} ago'
+    TIMEDIFFIN: 'in {difference}'
     YEAR: ' year'
     YEARS: ' years'
   DateField:
     NOTSET: 'not set'
     TODAY: today
-    VALIDDATEFORMAT2: 'Please enter a valid date format (%s).'
-    VALIDDATEMAXDATE: 'Your date has to be older or matching the maximum allowed date (%s)'
-    VALIDDATEMINDATE: 'Your date has to be newer or matching the minimum allowed date (%s)'
+    VALIDDATEFORMAT2: 'Please enter a valid date format ({format}).'
+    VALIDDATEMAXDATE: 'Your date has to be older or matching the maximum allowed date ({date})'
+    VALIDDATEMINDATE: 'Your date has to be newer or matching the minimum allowed date ({date})'
   DropdownField:
     CHOOSE: (Choose)
   EmailField:
@@ -130,24 +130,24 @@ en:
   File:
     Content: Content
     Filename: Filename
-    INVALIDEXTENSION: 'Extension is not allowed (valid: %s)'
+    INVALIDEXTENSION: 'Extension is not allowed (valid: {extensions})'
     NOFILESIZE: 'Filesize is zero bytes.'
     NOVALIDUPLOAD: 'File is not a valid upload'
     Name: Name
     PLURALNAME: Files
     SINGULARNAME: File
-    TOOLARGE: 'Filesize is too large, maximum %s allowed.'
+    TOOLARGE: 'Filesize is too large, maximum {size} allowed.'
     Title: Title
   FileIFrameField:
-    ATTACH: 'Attach %s'
-    ATTACHONCESAVED: '%ss can be attached once you have saved the record for the first time.'
-    DELETE: 'Delete %s'
+    ATTACH: 'Attach {type}'
+    ATTACHONCESAVED: '{type}s can be attached once you have saved the record for the first time.'
+    DELETE: 'Delete {type}'
     DISALLOWEDFILETYPE: 'This filetype is not allowed to be uploaded'
     FILE: File
     FROMCOMPUTER: 'From your Computer'
     FROMFILESTORE: 'From the File Store'
     NOSOURCE: 'Please select a source file to attach'
-    REPLACE: 'Replace %s'
+    REPLACE: 'Replace {type}'
   FileIFrameField_iframe.ss:
     TITLE: 'Image Uploading Iframe'
   ForgotPasswordEmail.ss:
@@ -157,8 +157,7 @@ en:
     TEXT3: for
   Form:
     FIELDISREQUIRED: '%s is required'
-    VALIDATIONCREDITNUMBER: 'Please ensure you have entered the %s credit card number correctly.'
-    VALIDATIONFAILED: 'Validation failed'
+    VALIDATIONCREDITNUMBER: 'Please ensure you have entered the {number} credit card number correctly.'
     VALIDATIONNOTUNIQUE: 'The value entered is not unique'
     VALIDATIONPASSWORDSDONTMATCH: 'Passwords don''t match'
     VALIDATIONPASSWORDSNOTEMPTY: 'Passwords can''t be empty'
@@ -179,8 +178,8 @@ en:
     NoItemsFound: 'No items found'
     PRINTEDAT: 'Printed at'
     PRINTEDBY: 'Printed by'
-    PlaceHolder: 'Find %s'
-    PlaceHolderWithLabels: 'Find %s by %s'
+    PlaceHolder: 'Find {type}'
+    PlaceHolderWithLabels: 'Find {type} by {name}'
     RelationSearch: 'Relation search'
     ResetFilter: Reset
   GridFieldAction_Delete:
@@ -209,16 +208,17 @@ en:
   GroupImportForm:
     Help1: '<p>Import one or more groups in <em>CSV</em> format (comma-separated values). <small><a href="#" class="toggle-advanced">Show advanced usage</a></small></p>'
     Help2: "<div class=\"advanced\">\n	<h4>Advanced usage</h4>\n	<ul>\n	<li>Allowed columns: <em>%s</em></li>\n	<li>Existing groups are matched by their unique <em>Code</em> value, and updated with any new values from the imported file</li>\n	<li>Group hierarchies can be created by using a <em>ParentCode</em> column.</li>\n	<li>Permission codes can be assigned by the <em>PermissionCode</em> column. Existing permission codes are not cleared.</li>\n	</ul>\n</div>"
-    ResultCreated: 'Created %d groups'
+    ResultCreated: 'Created {count} groups'
     ResultDeleted: 'Deleted %d groups'
     ResultUpdated: 'Updated %d groups'
   Hierarchy:
-    InfiniteLoopNotAllowed: 'Infinite loop found within the "%s" hierarchy. Please change the parent to resolve this'
+    InfiniteLoopNotAllowed: 'Infinite loop found within the "{type}" hierarchy. Please change the parent to resolve this'
   HtmlEditorField:
     ANCHORVALUE: Anchor
     BUTTONINSERT: Insert
     BUTTONINSERTLINK: 'Insert link'
     BUTTONREMOVELINK: 'Remove link'
+    BUTTONUpdate: Update
     CAPTIONTEXT: 'Caption text'
     CSSCLASS: 'Alignment / style'
     CSSCLASSCENTER: 'Centered, on its own.'
@@ -233,12 +233,12 @@ en:
     FROMCMS: 'From the CMS'
     FROMCOMPUTER: 'From your computer'
     Find: Find
-    IMAGE: 'Insert Image'
     IMAGEALTTEXT: 'Alternative text (alt) - shown if image cannot be displayed'
     IMAGEDIMENSIONS: Dimensions
     IMAGEHEIGHTPX: Height
     IMAGETITLE: 'Title text (tooltip) - for additional information about the image'
     IMAGEWIDTHPX: Width
+    INSERTIMAGE: 'Insert Image'
     LINK: 'Insert Link'
     LINKANCHOR: 'Anchor on this page'
     LINKDESCR: 'Link description'
@@ -250,6 +250,7 @@ en:
     LINKTO: 'Link to'
     PAGE: Page
     URL: URL
+    UpdateIMAGE: 'Update Image'
   ImageField:
     IMAGE: Image
   Image_iframe.ss:
@@ -270,6 +271,7 @@ en:
     IP: 'IP Address'
     Status: Status
   Member:
+    ADDGROUP: 'Add group'
     ADDRESS: Address
     BUTTONCHANGEPASSWORD: 'Change Password'
     BUTTONLOGIN: 'Log in'
@@ -293,8 +295,8 @@ en:
     FIRSTNAME: 'First Name'
     GREETING: Welcome
     INTERFACELANG: 'Interface Language'
-    INVALIDNEWPASSWORD: 'We couldn''t accept that password: %s'
-    LOGGEDINAS: 'You''re logged in as %s.'
+    INVALIDNEWPASSWORD: 'We couldn''t accept that password: {password}'
+    LOGGEDINAS: 'You''re logged in as {name}.'
     MOBILE: Mobile
     NAME: Name
     NEWPASSWORD: 'New Password'
@@ -308,8 +310,8 @@ en:
     SUBJECTPASSWORDRESET: 'Your password reset link'
     SURNAME: Surname
     VALIDATIONMEMBEREXISTS: 'A member already exists with the same %s'
-    ValidationIdentifierFailed: 'Can''t overwrite existing member #%d with identical identifier (%s = %s))'
-    WELCOMEBACK: 'Welcome Back, %s'
+    ValidationIdentifierFailed: 'Can''t overwrite existing member #{id} with identical identifier ({name} = {value}))'
+    WELCOMEBACK: 'Welcome Back, {firstname}'
     YOUROLDPASSWORD: 'Your old password'
     belongs_many_many_Groups: Groups
     db_LastVisited: 'Last Visited Date'
@@ -343,37 +345,37 @@ en:
   MemberImportForm:
     Help1: '<p>Import users in <em>CSV format</em> (comma-separated values). <small><a href="#" class="toggle-advanced">Show advanced usage</a></small></p>'
     Help2: "<div class=\"advanced\">\n	<h4>Advanced usage</h4>\n	<ul>\n	<li>Allowed columns: <em>%s</em></li>\n	<li>Existing users are matched by their unique <em>Code</em> property, and updated with any new values from the imported file.</li>\n	<li>Groups can be assigned by the <em>Groups</em> column. Groups are identified by their <em>Code</em> property, multiple groups can be separated by comma. Existing group memberships are not cleared.</li>\n	</ul>\n</div>"
-    ResultCreated: 'Created %d members'
+    ResultCreated: 'Created {count} members'
     ResultDeleted: 'Deleted %d members'
     ResultNone: 'No changes'
-    ResultUpdated: 'Updated %d members'
+    ResultUpdated: 'Updated {count} members'
   MemberTableField:
     'APPLY FILTER': 'Apply Filter'
   ModelAdmin:
     DELETE: Delete
-    DELETEDRECORDS: 'Deleted %s records.'
+    DELETEDRECORDS: 'Deleted {count} records.'
     IMPORT: 'Import from CSV'
-    IMPORTEDRECORDS: 'Imported %s records.'
+    IMPORTEDRECORDS: 'Imported {count} records.'
     NOCSVFILE: 'Please browse for a CSV file to import'
     NOIMPORT: 'Nothing to import'
     RESET: Reset
-    UPDATEDRECORDS: 'Updated %s records.'
+    UPDATEDRECORDS: 'Updated {count} records.'
   MoneyField:
     FIELDLABELAMOUNT: Amount
     FIELDLABELCURRENCY: Currency
   NullableField:
     IsNullLabel: 'Is Null'
   NumericField:
-    VALIDATION: '''%s'' is not a number, only numbers can be accepted for this field'
+    VALIDATION: '''{value}'' is not a number, only numbers can be accepted for this field'
   Permission:
     AdminGroup: Administrator
     CMS_ACCESS_CATEGORY: 'CMS Access'
     FULLADMINRIGHTS: 'Full administrative rights'
     FULLADMINRIGHTS_HELP: 'Implies and overrules all other assigned permissions.'
   PermissionCheckboxSetField:
-    AssignedTo: 'assigned to "%s"'
-    FromGroup: 'inherited from group "%s"'
-    FromRole: 'inherited from role "%s"'
+    AssignedTo: 'assigned to "{title}"'
+    FromGroup: 'inherited from group "{title}"'
+    FromRole: 'inherited from role "{title}"'
     FromRoleOnGroup: 'inherited from role "%s" on group "%s"'
   Permissions:
     PERMISSIONS_CATEGORY: 'Roles and access permissions'
@@ -391,10 +393,10 @@ en:
     LOGGEDOUT: 'You have been logged out.  If you would like to log in again, enter your credentials below.'
     LOGIN: 'Log in'
     NOTEPAGESECURED: 'That page is secured. Enter your credentials below and we will send you right along.'
-    NOTERESETLINKINVALID: '<p>The password reset link is invalid or expired.</p><p>You can request a new one <a href="%s">here</a> or change your password after you <a href="%s">logged in</a>.</p>'
+    NOTERESETLINKINVALID: '<p>The password reset link is invalid or expired.</p><p>You can request a new one <a href="{link1}">here</a> or change your password after you <a href="{link2}">logged in</a>.</p>'
     NOTERESETPASSWORD: 'Enter your e-mail address and we will send you a link with which you can reset your password'
-    PASSWORDSENTHEADER: 'Password reset link sent to ''%s'''
-    PASSWORDSENTTEXT: 'Thank you! A reset link has been sent to  ''%s'', provided an account exists for this email address.'
+    PASSWORDSENTHEADER: 'Password reset link sent to ''{email}'''
+    PASSWORDSENTTEXT: 'Thank you! A reset link has been sent to ''{email}'', provided an account exists for this email address.'
   SecurityAdmin:
     ACCESS_HELP: 'Allow viewing, adding and editing users, as well as assigning permissions and roles to them.'
     APPLY_ROLES: 'Apply roles to groups'
@@ -440,7 +442,7 @@ en:
   TextareaField_Readonly.ss:
     NONE: none
   TimeField:
-    VALIDATEFORMAT: 'Please enter a valid time format (%s)'
+    VALIDATEFORMAT: 'Please enter a valid time format ({format})'
   ToggleCompositeField.ss:
     HIDE: Hide
     SHOW: Show
@@ -459,7 +461,7 @@ en:
     FIELDNOTSET: 'File information not found'
     FROMCOMPUTER: 'From your computer'
     FROMFILES: 'From files'
-    MAXNUMBEROFFILES: 'Max number of %s file(s) exceeded.'
+    MAXNUMBEROFFILES: 'Max number of {count} file(s) exceeded.'
     REMOVEERROR: 'Error removing file'
     REMOVEINFO: 'Remove this file from here, but do not delete it from the file store'
     STARTALL: 'Start all'
diff --git a/model/Hierarchy.php b/model/Hierarchy.php
index 48ad13889..dbec83d1f 100644
--- a/model/Hierarchy.php
+++ b/model/Hierarchy.php
@@ -44,13 +44,11 @@ class Hierarchy extends DataExtension {
 			if ($node->ParentID==$this->owner->ID) {
 				// Hierarchy is looping.
 				$validationResult->error(
-					sprintf(
-						_t(
-							'Hierarchy.InfiniteLoopNotAllowed',
-							'Infinite loop found within the "%s" hierarchy. Please change the parent to resolve this',
-							'First argument is the class that makes up the hierarchy.'
-						),
-						$this->owner->class
+					_t(
+						'Hierarchy.InfiniteLoopNotAllowed',
+						'Infinite loop found within the "{type}" hierarchy. Please change the parent to resolve this',
+						'First argument is the class that makes up the hierarchy.',
+						array('type' => $this->owner->class)
 					),
 					'INFINITE_LOOP'
 				);
diff --git a/model/fieldtypes/Date.php b/model/fieldtypes/Date.php
index 7de0cca95..269c93df8 100644
--- a/model/fieldtypes/Date.php
+++ b/model/fieldtypes/Date.php
@@ -191,24 +191,18 @@ class Date extends DBField {
 	function Ago() {
 		if($this->value) {
 			if(strtotime($this->value) == time() || time() > strtotime($this->value)) {
-				return sprintf(
-					_t(
-						'Date.TIMEDIFFAGO',
-						"%s ago",
-						
-						'Natural language time difference, e.g. 2 hours ago'
-					),
-					$this->TimeDiff()
+				return _t(
+					'Date.TIMEDIFFAGO',
+					"{difference} ago",
+					'Natural language time difference, e.g. 2 hours ago',
+					array('difference' => $this->TimeDiff())
 				);
 			} else {
-				return sprintf(
-					_t(
-						'Date.TIMEDIFFIN',
-						"in %s",
-						
-						'Natural language time difference, e.g. in 2 hours'
-					),
-					$this->TimeDiff()
+				return _t(
+					'Date.TIMEDIFFIN',
+					"in {difference}",
+					'Natural language time difference, e.g. in 2 hours',
+					array('difference' => $this->TimeDiff())
 				);
 			}
 		}
diff --git a/security/ChangePasswordForm.php b/security/ChangePasswordForm.php
index cb218e6f0..53b21b394 100644
--- a/security/ChangePasswordForm.php
+++ b/security/ChangePasswordForm.php
@@ -117,7 +117,11 @@ class ChangePasswordForm extends Form {
 			} else {
 				$this->clearMessage();
 				$this->sessionMessage(
-					sprintf(_t('Member.INVALIDNEWPASSWORD', "We couldn't accept that password: %s"), nl2br("\n".$isValid->starredList())), 
+					_t(
+						'Member.INVALIDNEWPASSWORD', 
+						"We couldn't accept that password: {password}",
+						array('password' => nl2br("\n".$isValid->starredList()))
+					), 
 					"bad"
 				);
 				Director::redirectBack();
diff --git a/security/Member.php b/security/Member.php
index a7774f981..0558c28d6 100644
--- a/security/Member.php
+++ b/security/Member.php
@@ -626,16 +626,15 @@ class Member extends DataObject implements TemplateGlobalProvider {
 				)
 			);
 			if($existingRecord) {
-				throw new ValidationException(new ValidationResult(false, sprintf(
-					_t(
-						'Member.ValidationIdentifierFailed', 
-						'Can\'t overwrite existing member #%d with identical identifier (%s = %s))', 
-						
-						'The values in brackets show a fieldname mapped to a value, usually denoting an existing email address'
-					),
-					$existingRecord->ID,
-					$identifierField,
-					$this->$identifierField
+				throw new ValidationException(new ValidationResult(false, _t(
+					'Member.ValidationIdentifierFailed', 
+					'Can\'t overwrite existing member #{id} with identical identifier ({name} = {value}))', 
+					'The values in brackets show a fieldname mapped to a value, usually denoting an existing email address',
+					array(
+						'id' => $existingRecord->ID,
+						'name' => $identifierField,
+						'value' => $this->$identifierField
+					)
 				)));
 			}
 		}
@@ -1624,12 +1623,10 @@ class Member_Validator extends RequiredFields {
 			$uniqueField = $this->form->dataFieldByName($identifierField);
 			$this->validationError(
 				$uniqueField->id(),
-				sprintf(
-					_t(
-						'Member.VALIDATIONMEMBEREXISTS',
-						'A member already exists with the same %s'
-					),
-					strtolower($identifierField)
+				_t(
+					'Member.VALIDATIONMEMBEREXISTS',
+					'A member already exists with the same %s',
+					array('identifier' => strtolower($identifierField))
 				),
 				'required'
 			);
diff --git a/security/MemberLoginForm.php b/security/MemberLoginForm.php
index 0299e181f..538824453 100644
--- a/security/MemberLoginForm.php
+++ b/security/MemberLoginForm.php
@@ -105,7 +105,11 @@ JS
 	protected function getMessageFromSession() {
 		parent::getMessageFromSession();
 		if(($member = Member::currentUser()) && !Session::get('MemberLoginForm.force_message')) {
-			$this->message = sprintf(_t('Member.LOGGEDINAS', "You're logged in as %s."), $member->{$this->loggedInAsField});
+			$this->message = _t(
+				'Member.LOGGEDINAS', 
+				"You're logged in as {name}.", 
+				array('name' => $member->{$this->loggedInAsField})
+			);
 		}
 		Session::set('MemberLoginForm.force_message', false);
 	}
@@ -198,7 +202,7 @@ JS
 			}
 
 			Session::set('Security.Message.message',
-				sprintf(_t('Member.WELCOMEBACK', "Welcome Back, %s"), $firstname)
+				_t('Member.WELCOMEBACK', "Welcome Back, {firstname}", array('firstname' => $firstname))
 			);
 			Session::set("Security.Message.type", "good");
 		}
diff --git a/security/PermissionCheckboxSetField.php b/security/PermissionCheckboxSetField.php
index 4f37bb854..03f639242 100644
--- a/security/PermissionCheckboxSetField.php
+++ b/security/PermissionCheckboxSetField.php
@@ -96,9 +96,9 @@ class PermissionCheckboxSetField extends FormField {
 			$relationMethod = $this->name;
 			foreach($record->$relationMethod() as $permission) {
 				if(!isset($uninheritedCodes[$permission->Code])) $uninheritedCodes[$permission->Code] = array();
-				$uninheritedCodes[$permission->Code][] = sprintf(
-					_t('PermissionCheckboxSetField.AssignedTo', 'assigned to "%s"'),
-					$record->Title
+				$uninheritedCodes[$permission->Code][] = _t(
+					'PermissionCheckboxSetField.AssignedTo', 'assigned to "{title}"',
+					array('title' => $record->Title)
 				);
 			}
 
@@ -110,14 +110,11 @@ class PermissionCheckboxSetField extends FormField {
 					foreach($record->Roles() as $role) {
 						foreach($role->Codes() as $code) {
 							if (!isset($inheritedCodes[$code->Code])) $inheritedCodes[$code->Code] = array();
-							$inheritedCodes[$code->Code][] = sprintf(
-								_t(
-									'PermissionCheckboxSetField.FromRole',
-									'inherited from role "%s"',
-									
-									'A permission inherited from a certain permission role'
-								),
-								$role->Title
+							$inheritedCodes[$code->Code][] = _t(
+								'PermissionCheckboxSetField.FromRole',
+								'inherited from role "{title}"',
+								'A permission inherited from a certain permission role',
+								array('title' => $role->Title)
 							);
 						}
 					}
@@ -132,15 +129,11 @@ class PermissionCheckboxSetField extends FormField {
 							if ($role->Codes()) {
 								foreach($role->Codes() as $code) {
 									if (!isset($inheritedCodes[$code->Code])) $inheritedCodes[$code->Code] = array();
-									$inheritedCodes[$code->Code][] = sprintf(
-										_t(
-											'PermissionCheckboxSetField.FromRoleOnGroup',
-											'inherited from role "%s" on group "%s"',
-											
-											'A permission inherited from a role on a certain group'
-										),
-										$role->Title, 
-										$parent->Title
+									$inheritedCodes[$code->Code][] = _t(
+										'PermissionCheckboxSetField.FromRoleOnGroup',
+										'inherited from role "%s" on group "%s"',
+										'A permission inherited from a role on a certain group',
+										array('roletitle' => $role->Title, 'grouptitle' => $parent->Title)
 									);
 								}
 							}
@@ -149,14 +142,11 @@ class PermissionCheckboxSetField extends FormField {
 							foreach($parent->Permissions() as $permission) {
 								if (!isset($inheritedCodes[$permission->Code])) $inheritedCodes[$permission->Code] = array();
 								$inheritedCodes[$permission->Code][] = 
-								sprintf(
-									_t(
-										'PermissionCheckboxSetField.FromGroup',
-										'inherited from group "%s"',
-										
-										'A permission inherited from a certain group'
-									),
-									$parent->Title
+								_t(
+									'PermissionCheckboxSetField.FromGroup',
+									'inherited from group "{title}"',
+									'A permission inherited from a certain group',
+									array('title' => $parent->Title)
 								);
 							}
 						}
diff --git a/security/Security.php b/security/Security.php
index 29765ec96..1d07d7318 100644
--- a/security/Security.php
+++ b/security/Security.php
@@ -494,10 +494,10 @@ class Security extends Controller {
 		$email = Convert::raw2xml(rawurldecode($request->param('ID')) . '.' . $request->getExtension());
 
 		$customisedController = $controller->customise(array(
-			'Title' => sprintf(_t('Security.PASSWORDSENTHEADER', "Password reset link sent to '%s'"), $email),
+			'Title' => _t('Security.PASSWORDSENTHEADER', "Password reset link sent to '{email}'", array('email' => $email)),
 			'Content' =>
 				"<p>" . 
-				sprintf(_t('Security.PASSWORDSENTTEXT', "Thank you! A reset link has been sent to  '%s', provided an account exists for this email address."), $email) .
+				_t('Security.PASSWORDSENTTEXT', "Thank you! A reset link has been sent to '{email}', provided an account exists for this email address.", array('email' => $email)) .
 				"</p>",
 			'Email' => $email
 		));
@@ -571,12 +571,10 @@ class Security extends Controller {
 			if(isset($_REQUEST['h'])) {
 				$customisedController = $controller->customise(
 					array('Content' =>
-						sprintf(
-							_t('Security.NOTERESETLINKINVALID',
-								'<p>The password reset link is invalid or expired.</p><p>You can request a new one <a href="%s">here</a> or change your password after you <a href="%s">logged in</a>.</p>'
-							),
-							$this->Link('lostpassword'),
-							$this->link('login')
+						_t(
+							'Security.NOTERESETLINKINVALID',
+							'<p>The password reset link is invalid or expired.</p><p>You can request a new one <a href="{link1}">here</a> or change your password after you <a href="{link2}">logged in</a>.</p>',
+							array('link1' => $this->Link('lostpassword'), 'link2' => $this->link('login'))
 						)
 					)
 				);
diff --git a/tests/filesystem/UploadTest.php b/tests/filesystem/UploadTest.php
index 8816d00b5..d3f112384 100644
--- a/tests/filesystem/UploadTest.php
+++ b/tests/filesystem/UploadTest.php
@@ -333,28 +333,22 @@ class UploadTest_Validator extends Upload_Validator implements TestOnly {
 		if(!$this->isValidSize()) {
 			$ext = (isset($pathInfo['extension'])) ? $pathInfo['extension'] : '';
 			$arg = File::format_size($this->getAllowedMaxFileSize($ext));
-			$this->errors[] = sprintf(
-				_t(
-					'File.TOOLARGE', 
-					'Filesize is too large, maximum %s allowed.',
-					
-					'Argument 1: Filesize (e.g. 1MB)'
-				),
-				$arg
+			$this->errors[] = _t(
+				'File.TOOLARGE', 
+				'Filesize is too large, maximum {size} allowed.',
+				'Argument 1: Filesize (e.g. 1MB)',
+				array('size' => $arg)
 			);
 			return false;
 		}
 
 		// extension validation
 		if(!$this->isValidExtension()) {
-			$this->errors[] = sprintf(
-				_t(
-					'File.INVALIDEXTENSION', 
-					'Extension is not allowed (valid: %s)',
-					
-					'Argument 1: Comma-separated list of valid extensions'
-				),
-				implode(',', $this->allowedExtensions)
+			$this->errors[] = _t(
+				'File.INVALIDEXTENSION', 
+				'Extension is not allowed (valid: {extensions})',
+				'Argument 1: Comma-separated list of valid extensions',
+				array('extensions' => implode(',', $this->allowedExtensions))
 			);
 			return false;
 		}
diff --git a/tests/i18n/i18nTest.php b/tests/i18n/i18nTest.php
index 7c5a40c84..ca0ac6392 100644
--- a/tests/i18n/i18nTest.php
+++ b/tests/i18n/i18nTest.php
@@ -251,7 +251,8 @@ class i18nTest extends SapphireTest {
 
 		i18n::get_translator('core')->getAdapter()->addTranslation(array(
 			'i18nTestModule.NEWMETHODSIG' => 'TRANS New _t method signature test',
-			'i18nTestModule.INJECTIONS' => 'TRANS Hello {name} {greeting}. But it is late, {goodbye}'
+			'i18nTestModule.INJECTIONS' => 'TRANS Hello {name} {greeting}. But it is late, {goodbye}',
+			'i18nTestModule.INJECTIONSLEGACY' => 'TRANS Hello %s %s. But it is late, %s',
 		), 'en_US');
 
 		$entity = "i18nTestModule.INJECTIONS";
@@ -287,6 +288,24 @@ class i18nTest extends SapphireTest {
 			$translated, "Testing a translation with just entity and injection array"
 		);
 
+		$translated = i18n::_t(
+			'i18nTestModule.INJECTIONSLEGACY', // has %s placeholders
+			array("name"=>"Cat", "greeting2"=>"meow", "goodbye"=>"meow")
+		);
+		$this->assertContains(
+			"TRANS Hello Cat meow. But it is late, meow",
+			$translated, "Testing sprintf placeholders with named injections"
+		);
+
+		$translated = i18n::_t(
+			'i18nTestModule.INJECTIONS', // has {name} placeholders
+			array("Cat", "meow", "meow")
+		);
+		$this->assertContains(
+			"TRANS Hello Cat meow. But it is late, meow",
+			$translated, "Testing named injection placeholders with unnamed injections"
+		);
+
 		i18n::set_locale($oldLocale);
 	}