diff --git a/Source/libgnustep-base.def b/Source/libgnustep-base.def
index 675ccd2bc..24e864568 100644
--- a/Source/libgnustep-base.def
+++ b/Source/libgnustep-base.def
@@ -240,3 +240,5 @@ __objc_class_name_GSXMLParser
 __objc_class_name_GCObject
 __objc_class_name_GCArray
 __objc_class_name_GCDictionary
+__objc_class_name_GCMutableArray
+__objc_class_name_GCMutableDictionary