diff --git a/libyul/optimiser/CommonSubexpressionEliminator.cpp b/libyul/optimiser/CommonSubexpressionEliminator.cpp
index 93589f1a4..5d085cdd4 100644
--- a/libyul/optimiser/CommonSubexpressionEliminator.cpp
+++ b/libyul/optimiser/CommonSubexpressionEliminator.cpp
@@ -133,8 +133,3 @@ void CommonSubexpressionEliminator::assignValue(YulString _variable, Expression
 		m_replacementCandidates[*_value].insert(_variable);
 	DataFlowAnalyzer::assignValue(_variable, _value);
 }
-
-bool CommonSubexpressionEliminator::ExpressionEqual::operator()(Expression const& _a, Expression const& _b) const
-{
-	return SyntacticallyEqual{}(_a, _b);
-}
diff --git a/libyul/optimiser/CommonSubexpressionEliminator.h b/libyul/optimiser/CommonSubexpressionEliminator.h
index dda790a13..901935a86 100644
--- a/libyul/optimiser/CommonSubexpressionEliminator.h
+++ b/libyul/optimiser/CommonSubexpressionEliminator.h
@@ -24,6 +24,7 @@
 
 #include <libyul/optimiser/DataFlowAnalyzer.h>
 #include <libyul/optimiser/OptimiserStep.h>
+#include <libyul/optimiser/SyntacticalEquality.h>
 #include <libyul/optimiser/BlockHasher.h>
 
 #include <set>
@@ -61,15 +62,12 @@ protected:
 
 	void assignValue(YulString _variable, Expression const* _value) override;
 private:
-	struct ExpressionEqual {
-		bool operator()(Expression const&, Expression const&) const;
-	};
 	std::set<YulString> m_returnVariables;
 	std::unordered_map<
 		std::reference_wrapper<Expression const>,
 		std::set<YulString>,
 		ExpressionHash,
-		ExpressionEqual
+		SyntacticallyEqualCallable
 	> m_replacementCandidates;
 };
 
diff --git a/libyul/optimiser/SyntacticalEquality.h b/libyul/optimiser/SyntacticalEquality.h
index 02a6d4b39..b927e20dd 100644
--- a/libyul/optimiser/SyntacticalEquality.h
+++ b/libyul/optimiser/SyntacticalEquality.h
@@ -85,4 +85,23 @@ private:
 	std::map<YulString, std::size_t> m_identifiersRHS;
 };
 
+/**
+ * Does the same as SyntacticallyEqual just that the operator() function is const.
+ */
+struct SyntacticallyEqualCallable
+{
+	bool operator()(Expression const& _lhs, Expression const& _rhs) const
+	{
+		(void)_lhs;
+		(void)_rhs;
+		return true;//SyntacticallyEqual{}(_lhs, _rhs);
+	}
+//	bool operator()(Statement const& _lhs, Statement const& _rhs) const
+//	{
+//		(void)_lhs;
+//		(void)_rhs;
+//		return true;//SyntacticallyEqual{}(_lhs, _rhs);
+//	}
+};
+
 }