diff --git a/core/Object.php b/core/Object.php
index 395acca12..d13ccc7ae 100755
--- a/core/Object.php
+++ b/core/Object.php
@@ -418,9 +418,12 @@ abstract class Object {
 		
 		// merge with existing static vars
 		$extensions = self::uninherited_static($class, 'extensions');
+		
 		// We use unshift rather than push so that module extensions are added before built-in ones.
 		// in particular, this ensures that the Versioned rewriting is done last.
-		array_unshift($extensions, $extension);
+		if($extensions) array_unshift($extensions, $extension);
+		else $extensions = array($extension);
+		
 		self::set_static($class, 'extensions', $extensions);
 		
 		// load statics now for DataObject classes