diff --git a/ChangeLog b/ChangeLog
index ade383465..5f74e2001 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,7 +1,9 @@
 2004-07-03 Richard Frith-Macdonald <rfm@gnu.org>
 
-	* Tools/plmerge.m: Bugfix ... was attempting to set values in a
-	dictionary which was not mutable.
+	* Tools/plmerge.m: Portability ... was attempting to set values in a
+	dictionary which may not be mutable.
+	* Source/NSString.m: ([propertyList]) make decoded containers mutable
+	for compatibility with current MacOS-X
 
 2004-07-02 Richard Frith-Macdonald <rfm@gnu.org>
 
diff --git a/Source/NSString.m b/Source/NSString.m
index b7e545002..7caf21932 100644
--- a/Source/NSString.m
+++ b/Source/NSString.m
@@ -4418,7 +4418,7 @@ handle_printf_atsign (FILE *stream,
 
   result = [NSPropertyListSerialization
     propertyListFromData: data
-    mutabilityOption: NSPropertyListImmutable
+    mutabilityOption: NSPropertyListMutableContainers
     format: &format
     errorDescription: &error];