--- a/js/src/ion/IonBuilder.cpp
+++ b/js/src/ion/IonBuilder.cpp
@@ -3026,19 +3026,17 @@ IonBuilder::addTypeBarrier(uint32_t i, C
         ins = callinfo.thisArg();
         callerObs = callinfo.thisType();
     } else {
         ins = callinfo.getArg(i - 1);
         callerObs = callinfo.getArgType(i - 1);
     }
 
     while (excluded) {
-        if (excluded->target == calleeObs) {
-            JS_ASSERT(callerObs->hasType(excluded->type));
-
+        if (excluded->target == calleeObs && callerObs->hasType(excluded->type)) {
             if (excluded->type == types::Type::DoubleType() &&
                 calleeObs->hasType(types::Type::Int32Type())) {
                 // The double type also implies int32, so this implies that
                 // double should be coerced into int if possible, and other
                 // types should remain.
 
                 JSValueType callerType = callerObs->getKnownTypeTag();
                 if (callerType == JSVAL_TYPE_DOUBLE) {