--- a/js/src/vm/EnvironmentObject.cpp
+++ b/js/src/vm/EnvironmentObject.cpp
@@ -3182,17 +3182,18 @@ js::GetDebugEnvironmentForGlobalLexicalE
 
 bool
 js::CreateObjectsForEnvironmentChain(JSContext* cx, AutoObjectVector& chain,
                                      HandleObject terminatingEnv, MutableHandleObject envObj)
 {
 #ifdef DEBUG
     for (size_t i = 0; i < chain.length(); ++i) {
         assertSameCompartment(cx, chain[i]);
-        MOZ_ASSERT(!chain[i]->is<GlobalObject>());
+        MOZ_ASSERT(!chain[i]->is<GlobalObject>() &&
+                   !chain[i]->is<NonSyntacticVariablesObject>());
     }
 #endif
 
     // Construct With object wrappers for the things on this environment chain
     // and use the result as the thing to scope the function to.
     Rooted<WithEnvironmentObject*> withEnv(cx);
     RootedObject enclosingEnv(cx, terminatingEnv);
     for (size_t i = chain.length(); i > 0; ) {