diff --git a/src/api.cc b/src/api.cc
index 338ae72abc..2ce394a3fb 100644
--- a/src/api.cc
+++ b/src/api.cc
@@ -6479,6 +6479,11 @@ Local<Context> NewContext(
     v8::MaybeLocal<Value> global_object, size_t context_snapshot_index,
     v8::DeserializeInternalFieldsCallback embedder_fields_deserializer) {
   i::Isolate* isolate = reinterpret_cast<i::Isolate*>(external_isolate);
+  // TODO(jkummerow): This is for crbug.com/713699. Remove it if it doesn't
+  // fail.
+  // Sanity-check that the isolate is initialized and usable.
+  CHECK(isolate->builtins()->Illegal()->IsCode());
+
   TRACE_EVENT_CALL_STATS_SCOPED(isolate, "v8", "V8.NewContext");
   LOG_API(isolate, Context, New);
   i::HandleScope scope(isolate);