diff --git a/lib/Runtime/ByteCode/ByteCodeEmitter.cpp b/lib/Runtime/ByteCode/ByteCodeEmitter.cpp
index 42f2edee1dd..d52e1962769 100644
--- a/lib/Runtime/ByteCode/ByteCodeEmitter.cpp
+++ b/lib/Runtime/ByteCode/ByteCodeEmitter.cpp
@@ -3351,8 +3351,10 @@ void ByteCodeGenerator::EmitOneFunction(ParseNode *pnode)
 
         DefineLabels(funcInfo);
 
-        if (pnode->sxFnc.HasNonSimpleParameterList())
+        if (pnode->sxFnc.HasNonSimpleParameterList() || !funcInfo->IsBodyAndParamScopeMerged())
         {
+            Assert(pnode->sxFnc.HasNonSimpleParameterList() || CONFIG_FLAG(ForceSplitScope));
+
             this->InitBlockScopedNonTemps(funcInfo->root->sxFnc.pnodeScopes, funcInfo);
 
             EmitDefaultArgs(funcInfo, pnode);
@@ -3395,8 +3397,9 @@ void ByteCodeGenerator::EmitOneFunction(ParseNode *pnode)
 
         DefineUserVars(funcInfo);
 
-        if (pnode->sxFnc.HasNonSimpleParameterList())
+        if (pnode->sxFnc.HasNonSimpleParameterList() || !funcInfo->IsBodyAndParamScopeMerged())
         {
+            Assert(pnode->sxFnc.HasNonSimpleParameterList() || CONFIG_FLAG(ForceSplitScope));
             this->InitBlockScopedNonTemps(funcInfo->root->sxFnc.pnodeBodyScope, funcInfo);
         }
         else