--- a/lib/kernel/atomics.cl
+++ b/lib/kernel/atomics.cl
@@ -152,9 +152,11 @@ T atomic_cmpxchg(volatile Q T *p, T cmp, T val)
   union { intptr_t i; volatile T *p; } u2;
   u1.p = p;
   u2.i = u1.i;
-  __atomic_compare_exchange_n(u2.p, &cmp, val, false,
-                              __ATOMIC_RELAXED, __ATOMIC_RELAXED);
-  return cmp;
+  if (!__atomic_compare_exchange_n(u2.p, &cmp, val, false,
+                                   __ATOMIC_RELAXED, __ATOMIC_RELAXED))
+    return cmp;
+  else
+    return val;
 }