diff --git a/gcc/c-family/ChangeLog b/gcc/c-family/ChangeLog
index 937fd6d1e28..20ef315ea74 100644
--- a/gcc/c-family/ChangeLog
+++ b/gcc/c-family/ChangeLog
@@ -1,3 +1,9 @@
+2012-11-09  Andi Kleen  <ak@linux.intel.com>
+
+	PR 55139
+	* c-common.c (get_atomic_generic_size): Mask with
+        MEMMODEL_MASK
+
 2012-11-07  Manuel López-Ibáñez  <manu@gcc.gnu.org>
 
 	PR c/53063
diff --git a/gcc/c-family/c-common.c b/gcc/c-family/c-common.c
index c3a64653471..7828d210507 100644
--- a/gcc/c-family/c-common.c
+++ b/gcc/c-family/c-common.c
@@ -10097,7 +10097,7 @@ get_atomic_generic_size (location_t loc, tree function, VEC(tree,gc) *params)
       if (TREE_CODE (p) == INTEGER_CST)
         {
 	  int i = tree_low_cst (p, 1);
-	  if (i < 0 || i >= MEMMODEL_LAST)
+	  if (i < 0 || (i & MEMMODEL_MASK) >= MEMMODEL_LAST)
 	    {
 	      warning_at (loc, OPT_Winvalid_memory_model,
 			  "invalid memory model argument %d of %qE", x + 1,