diff --git a/forms/DateField.php b/forms/DateField.php
index 848ca3d94..e0a408383 100755
--- a/forms/DateField.php
+++ b/forms/DateField.php
@@ -363,7 +363,7 @@ JS;
 			if(Zend_Date::isDate($min, $this->getConfig('datavalueformat'))) {
 				$minDate = new Zend_Date($min, $this->getConfig('datavalueformat'));
 			} else {
-				$minDate = new Zend_Date(strftime('%F', strtotime($min)), $this->getConfig('datavalueformat'));
+				$minDate = new Zend_Date(strftime('%Y-%m-%d', strtotime($min)), $this->getConfig('datavalueformat'));
 			}
 			if(!$this->valueObj->isLater($minDate) && !$this->valueObj->equals($minDate)) {
 				$validator->validationError(
@@ -383,7 +383,7 @@ JS;
 			if(Zend_Date::isDate($min, $this->getConfig('datavalueformat'))) {
 				$maxDate = new Zend_Date($max, $this->getConfig('datavalueformat'));
 			} else {
-				$maxDate = new Zend_Date(strftime('%F', strtotime($max)), $this->getConfig('datavalueformat'));
+				$maxDate = new Zend_Date(strftime('%Y-%m-%d', strtotime($max)), $this->getConfig('datavalueformat'));
 			}
 			if(!$this->valueObj->isEarlier($maxDate) && !$this->valueObj->equals($maxDate)) {
 				$validator->validationError(
diff --git a/tests/forms/DateFieldTest.php b/tests/forms/DateFieldTest.php
index cf0857dbe..b3c04fa47 100644
--- a/tests/forms/DateFieldTest.php
+++ b/tests/forms/DateFieldTest.php
@@ -38,24 +38,24 @@ class DateFieldTest extends SapphireTest {
 	function testValidateMinDateStrtotime() {
 		$f = new DateField('Date');
 		$f->setConfig('min', '-7 days');
-		$f->setValue(strftime('%F', strtotime('-8 days')));
+		$f->setValue(strftime('%Y-%m-%d', strtotime('-8 days')));
 		$this->assertFalse($f->validate(new RequiredFields()), 'Date below min date, with strtotime');
 		
 		$f = new DateField('Date');
 		$f->setConfig('min', '-7 days');
-		$f->setValue(strftime('%F', strtotime('-7 days')));
+		$f->setValue(strftime('%Y-%m-%d', strtotime('-7 days')));
 		$this->assertTrue($f->validate(new RequiredFields()), 'Date matching min date, with strtotime');
 	}
 	
 	function testValidateMaxDateStrtotime() {
 		$f = new DateField('Date');
 		$f->setConfig('max', '7 days');
-		$f->setValue(strftime('%F', strtotime('8 days')));
+		$f->setValue(strftime('%Y-%m-%d', strtotime('8 days')));
 		$this->assertFalse($f->validate(new RequiredFields()), 'Date above max date, with strtotime');
 		
 		$f = new DateField('Date');
 		$f->setConfig('max', '7 days');
-		$f->setValue(strftime('%F', strtotime('7 days')));
+		$f->setValue(strftime('%Y-%m-%d', strtotime('7 days')));
 		$this->assertTrue($f->validate(new RequiredFields()), 'Date matching max date, with strtotime');
 	}