diff --git a/src/Analyzer/QueryTreePassManager.cpp b/src/Analyzer/QueryTreePassManager.cpp
index 9c07884a464..2789423799a 100644
--- a/src/Analyzer/QueryTreePassManager.cpp
+++ b/src/Analyzer/QueryTreePassManager.cpp
@@ -269,6 +269,11 @@ void addQueryTreePasses(QueryTreePassManager & manager, bool only_analyze)
 
     manager.addPass(std::make_unique<AggregateFunctionsArithmericOperationsPass>());
     manager.addPass(std::make_unique<UniqInjectiveFunctionsEliminationPass>());
+
+    // Should run before optimization of GROUP BY keys to allow the removal of
+    // toString function.
+    manager.addPass(std::make_unique<IfTransformStringsToEnumPass>());
+
     manager.addPass(std::make_unique<OptimizeGroupByFunctionKeysPass>());
     manager.addPass(std::make_unique<OptimizeGroupByInjectiveFunctionsPass>());
 
@@ -285,7 +290,6 @@ void addQueryTreePasses(QueryTreePassManager & manager, bool only_analyze)
 
     manager.addPass(std::make_unique<FuseFunctionsPass>());
 
-    manager.addPass(std::make_unique<IfTransformStringsToEnumPass>());
 
     manager.addPass(std::make_unique<ConvertOrLikeChainPass>());