diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 14723f0909d..750362b40b9 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,7 @@
+2011-10-28  Paolo Carlini  <paolo.carlini@oracle.com>
+
+	* pt.c (unify_pack_expansion): Initialize bad_old_arg and bad_new_arg.
+
 2011-10-28  Paolo Carlini  <paolo.carlini@oracle.com>
 
 	PR c++/50864
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index dc63366358b..bd95096d613 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -15715,7 +15715,7 @@ unify_pack_expansion (tree tparms, tree targs, tree packed_parms,
         }
       else
 	{
-	  tree bad_old_arg, bad_new_arg;
+	  tree bad_old_arg = NULL_TREE, bad_new_arg = NULL_TREE;
 	  tree old_args = ARGUMENT_PACK_ARGS (old_pack);
 
 	  if (!comp_template_args_with_info (old_args, new_args,