diff --git a/Classes/PHPExcel/Shared/Date.php b/Classes/PHPExcel/Shared/Date.php
index 18e42c11..065ebe79 100644
--- a/Classes/PHPExcel/Shared/Date.php
+++ b/Classes/PHPExcel/Shared/Date.php
@@ -279,6 +279,8 @@ class PHPExcel_Shared_Date
 	public static function stringToExcel($dateValue = '') {
 		if (strlen($dateValue) < 2)
 			return false;
+		if (!preg_match('/^(\d{1,4}[ \.\/\-][A-Z]{3,9}([ \.\/\-]\d{1,4})?|[A-Z]{3,9}[ \.\/\-]\d{1,4}([ \.\/\-]\d{1,4})?|\d{1,4}[ \.\/\-]\d{1,4}([ \.\/\-]\d{1,4})?)( \d{1,2}:\d{1,2}(:\d{1,2})?)?$/iu', $dateValue))
+			return false;
 
 		$dateValueNew = PHPExcel_Calculation_DateTime::DATEVALUE($dateValue);
 
diff --git a/changelog.txt b/changelog.txt
index 969d4e9d..94b0d7ad 100644
--- a/changelog.txt
+++ b/changelog.txt
@@ -51,6 +51,7 @@ Fixed in SVN:
 - Bugfix:	(MBaker) Work item 15129 - Worksheet fromArray() only working with 2-D arrays
 - Bugfix:	(MBaker) Work item 15172 - rangeToarray function modified for non-existent cells
 - Bugfix:	(MBaker) Work item 14980 - Images not getting copyied with the ->clone function
+- Bugfix:	(MBaker) Work item 11576 - AdvancedValueBinder.php: String sometimes becomes a date when it shouldn't
 - General:  (MBaker) Improved performance (speed), for building the Shared Strings table in the Excel2007 Writer.