diff --git a/libyul/optimiser/OptimizerUtilities.cpp b/libyul/optimiser/OptimizerUtilities.cpp
index 2a3f7db90..52019356e 100644
--- a/libyul/optimiser/OptimizerUtilities.cpp
+++ b/libyul/optimiser/OptimizerUtilities.cpp
@@ -45,5 +45,5 @@ void yul::removeEmptyBlocks(Block& _block)
 
 bool yul::isRestrictedIdentifier(Dialect const& _dialect, YulString const& _identifier)
 {
-	return _identifier.empty() || TokenTraits::isYulKeyword(_identifier.str()) || _dialect.builtin(_identifier);
+	return _identifier.empty() || TokenTraits::isYulKeyword(_identifier.str()) || _dialect.reservedIdentifier(_identifier);
 }