diff --git a/control/injector/Injector.php b/control/injector/Injector.php
index 96c69854b..3ab429a29 100644
--- a/control/injector/Injector.php
+++ b/control/injector/Injector.php
@@ -866,7 +866,7 @@ class Injector {
 			return $this->instantiate($spec, $name);
 		}
 
-		return $this->instantiate($spec);
+		return $this->instantiate($spec, null, 'prototype');
 	}
 
 	/**
diff --git a/core/Object.php b/core/Object.php
index 0a28bae0a..21a741511 100644
--- a/core/Object.php
+++ b/core/Object.php
@@ -908,6 +908,10 @@ abstract class SS_Object {
 		$methods = $this->findMethodsFromExtension($extension);
 		if ($methods) {
 			foreach ($methods as $method) {
+				if (!isset(self::$extra_methods[$this->class][$method])) {
+					continue;
+				}
+				
 				$methodInfo = self::$extra_methods[$this->class][$method];
 
 				if ($methodInfo['property'] === $property && $methodInfo['index'] === $index) {
diff --git a/model/Versioned.php b/model/Versioned.php
index 399b2b50d..f525d5db1 100644
--- a/model/Versioned.php
+++ b/model/Versioned.php
@@ -446,7 +446,7 @@ class Versioned extends DataExtension implements TemplateGlobalProvider {
 
 		// Build a list of suffixes whose tables need versioning
 		$allSuffixes = array();
-		$versionableExtensions = $this->owner->config()->versionableExtensions;
+		$versionableExtensions = (array)$this->owner->config()->versionableExtensions;
 		if(count($versionableExtensions)){
 
 			foreach ($versionableExtensions as $versionableExtension => $suffixes) {
@@ -936,7 +936,7 @@ class Versioned extends DataExtension implements TemplateGlobalProvider {
 	 * @return string
 	 */
 	public function extendWithSuffix($table) {
-		$versionableExtensions = $this->owner->config()->versionableExtensions;
+		$versionableExtensions = (array)$this->owner->config()->versionableExtensions;
 
 		if(count($versionableExtensions)){
 			foreach ($versionableExtensions as $versionableExtension => $suffixes) {
diff --git a/tests/model/DataObjectTest.php b/tests/model/DataObjectTest.php
index e4fdb953e..ca51d30dc 100644
--- a/tests/model/DataObjectTest.php
+++ b/tests/model/DataObjectTest.php
@@ -39,6 +39,13 @@ class DataObjectTest extends SapphireTest {
 	 */
 	public function testSingleton($inst, $defaultValue, $altDefaultValue)
 	{
+		// Calls to scaffold the test database may have cached service specs for DataObjects
+		// with the incorrect 'type' set (singleton instead of prototype)
+		Injector::nest();
+		$reflectionProp = new ReflectionProperty('Injector', 'specs');
+		$reflectionProp->setAccessible(true);
+		$reflectionProp->setValue(Injector::inst(), array());
+
 		$inst = $inst();
 		// Test that populateDefaults() isn't called on singletons
 		// which can lead to SQL errors during build, and endless loops
@@ -53,6 +60,8 @@ class DataObjectTest extends SapphireTest {
 		} else {
 			$this->assertEmpty($inst->MyFieldWithAltDefault);
 		}
+
+		Injector::unnest();
 	}
 
 	public function provideSingletons()