diff --git a/ReactCommon/cxxreact/JSCExecutor.cpp b/ReactCommon/cxxreact/JSCExecutor.cpp
index 65a7e719b..c23e53e48 100644
--- a/ReactCommon/cxxreact/JSCExecutor.cpp
+++ b/ReactCommon/cxxreact/JSCExecutor.cpp
@@ -240,7 +240,9 @@ void JSCExecutor::initOnJSVMThread() throw(JSException) {
   JSClassRef globalClass = nullptr;
   {
     SystraceSection s("JSClassCreate");
-    globalClass = JSC_JSClassCreate(useCustomJSC, &kJSClassDefinitionEmpty);
+    JSClassDefinition definition = kJSClassDefinitionEmpty;
+    definition.attributes |= kJSClassAttributeNoAutomaticPrototype;
+    globalClass = JSC_JSClassCreate(useCustomJSC, &definition);
   }
   {
     SystraceSection s("JSGlobalContextCreateInGroup");
diff --git a/ReactCommon/jschelpers/JSCHelpers.cpp b/ReactCommon/jschelpers/JSCHelpers.cpp
index f99d76076..db6609a91 100644
--- a/ReactCommon/jschelpers/JSCHelpers.cpp
+++ b/ReactCommon/jschelpers/JSCHelpers.cpp
@@ -30,7 +30,8 @@ JSValueRef functionCaller(
 }
 
 JSClassRef createFuncClass(JSContextRef ctx) {
-  auto definition = kJSClassDefinitionEmpty;
+  JSClassDefinition definition = kJSClassDefinitionEmpty;
+  definition.attributes |= kJSClassAttributeNoAutomaticPrototype;
   // Need to duplicate the two different finalizer blocks, since there's no way
   // for it to capture this static information.
   if (isCustomJSCPtr(ctx)) {
@@ -107,7 +108,7 @@ void installGlobalProxy(
     const char* name,
     JSObjectGetPropertyCallback callback) {
   JSClassDefinition proxyClassDefintion = kJSClassDefinitionEmpty;
-  proxyClassDefintion.className = "_FBProxyClass";
+  proxyClassDefintion.attributes |= kJSClassAttributeNoAutomaticPrototype;
   proxyClassDefintion.getProperty = callback;
 
   const bool isCustomJSC = isCustomJSCPtr(ctx);