diff --git a/lib/Backend/GlobOptFields.cpp b/lib/Backend/GlobOptFields.cpp
index dbef6cd6898..318ce50d893 100644
--- a/lib/Backend/GlobOptFields.cpp
+++ b/lib/Backend/GlobOptFields.cpp
@@ -447,6 +447,15 @@ GlobOpt::ProcessFieldKills(IR::Instr *instr, BVSparse<JitArenaAllocator> *bv, bo
         }
         break;
 
+    case Js::OpCode::InitClass:
+    case Js::OpCode::InitProto:
+    case Js::OpCode::NewScObjectNoCtor:
+        if (inGlobOpt)
+        {
+            KillObjectHeaderInlinedTypeSyms(this->currentBlock, false);
+        }
+        break;
+
     default:
         if (instr->UsesAllFields())
         {
diff --git a/lib/Runtime/Library/JsBuiltInEngineInterfaceExtensionObject.cpp b/lib/Runtime/Library/JsBuiltInEngineInterfaceExtensionObject.cpp
index f5c0812bae3..fe552c77018 100644
--- a/lib/Runtime/Library/JsBuiltInEngineInterfaceExtensionObject.cpp
+++ b/lib/Runtime/Library/JsBuiltInEngineInterfaceExtensionObject.cpp
@@ -131,6 +131,26 @@ namespace Js
             return;
         }
 
+        struct AutoRestoreFlags
+        {
+            ThreadContext * ctx;
+            ImplicitCallFlags savedImplicitCallFlags;
+            DisableImplicitFlags savedDisableImplicitFlags;
+            AutoRestoreFlags(ThreadContext *ctx, Js::ImplicitCallFlags implFlags, DisableImplicitFlags disableImplFlags) :
+                ctx(ctx),
+                savedImplicitCallFlags(implFlags),
+                savedDisableImplicitFlags(disableImplFlags)
+            {
+                ctx->ClearDisableImplicitFlags();
+            }
+
+            ~AutoRestoreFlags()
+            {
+                ctx->SetImplicitCallFlags((Js::ImplicitCallFlags)(savedImplicitCallFlags));
+                ctx->SetDisableImplicitFlags((DisableImplicitFlags)savedDisableImplicitFlags);
+            }
+        };
+
         try {
             EnsureJsBuiltInByteCode(scriptContext);
             Assert(jsBuiltInByteCode != nullptr);
@@ -168,19 +188,19 @@ namespace Js
             scriptContext->GetThreadContext()->SetNoJsReentrancy(false);
 #endif
             // Clear disable implicit call bit as initialization code doesn't have any side effect
-            Js::ImplicitCallFlags saveImplicitCallFlags = scriptContext->GetThreadContext()->GetImplicitCallFlags();
-            scriptContext->GetThreadContext()->ClearDisableImplicitFlags();
-            JavascriptFunction::CallRootFunctionInScript(functionGlobal, Js::Arguments(callInfo, args));
-            scriptContext->GetThreadContext()->SetImplicitCallFlags((Js::ImplicitCallFlags)(saveImplicitCallFlags));
+            {
+                AutoRestoreFlags autoRestoreFlags(scriptContext->GetThreadContext(), scriptContext->GetThreadContext()->GetImplicitCallFlags(), scriptContext->GetThreadContext()->GetDisableImplicitFlags());
+                JavascriptFunction::CallRootFunctionInScript(functionGlobal, Js::Arguments(callInfo, args));
+            }
 
             Js::ScriptFunction *functionBuiltins = scriptContext->GetLibrary()->CreateScriptFunction(jsBuiltInByteCode->GetNestedFunctionForExecution(0));
             functionBuiltins->SetPrototype(scriptContext->GetLibrary()->nullValue);
 
             // Clear disable implicit call bit as initialization code doesn't have any side effect
-            saveImplicitCallFlags = scriptContext->GetThreadContext()->GetImplicitCallFlags();
-            scriptContext->GetThreadContext()->ClearDisableImplicitFlags();
-            JavascriptFunction::CallRootFunctionInScript(functionBuiltins, Js::Arguments(callInfo, args));
-            scriptContext->GetThreadContext()->SetImplicitCallFlags((Js::ImplicitCallFlags)(saveImplicitCallFlags));
+            {
+                AutoRestoreFlags autoRestoreFlags(scriptContext->GetThreadContext(), scriptContext->GetThreadContext()->GetImplicitCallFlags(), scriptContext->GetThreadContext()->GetDisableImplicitFlags());
+                JavascriptFunction::CallRootFunctionInScript(functionBuiltins, Js::Arguments(callInfo, args));
+            }
 
             InitializePrototypes(scriptContext);
 #if DBG_DUMP