diff --git a/libyul/optimiser/BlockHasher.h b/libyul/optimiser/BlockHasher.h
index f00f634d6..bdc27424e 100644
--- a/libyul/optimiser/BlockHasher.h
+++ b/libyul/optimiser/BlockHasher.h
@@ -134,4 +134,12 @@ public:
 	void operator()(FunctionCall const& _funCall) override;
 };
 
+struct ExpressionHash
+{
+	uint64_t operator()(Expression const& _expression) const
+	{
+		return ExpressionHasher{}.run(_expression);
+	}
+};
+
 }
diff --git a/libyul/optimiser/CommonSubexpressionEliminator.cpp b/libyul/optimiser/CommonSubexpressionEliminator.cpp
index 06c366cd5..be3c3c524 100644
--- a/libyul/optimiser/CommonSubexpressionEliminator.cpp
+++ b/libyul/optimiser/CommonSubexpressionEliminator.cpp
@@ -105,11 +105,8 @@ void CommonSubexpressionEliminator::visit(Expression& _e)
 					_e = Identifier{debugDataOf(_e), value->name};
 		}
 	}
-	else if (
-		auto it = m_replacementCandidates.find(&_e);
-		it != m_replacementCandidates.end()
-	)
-		for (auto const& variable: it->second)
+	else if (auto const* candidates = util::valueOrNullptr(m_replacementCandidates, _e))
+		for (auto const& variable: *candidates)
 			if (AssignedValue const* value = variableValue(variable))
 			{
 				assertThrow(value->value, OptimizerException, "");
@@ -133,16 +130,16 @@ void CommonSubexpressionEliminator::visit(Expression& _e)
 void CommonSubexpressionEliminator::assignValue(YulString _variable, Expression const* _value)
 {
 	if (_value)
-		m_replacementCandidates[_value].insert(_variable);
+		m_replacementCandidates[*_value].insert(_variable);
 	DataFlowAnalyzer::assignValue(_variable, _value);
 }
 
-uint64_t CommonSubexpressionEliminator::ExpressionHash::operator()(Expression const* _e) const
+uint64_t CommonSubexpressionEliminator::ExpressionHash::operator()(Expression const& _e) const
 {
-	return ExpressionHasher::run(*_e);
+	return ExpressionHasher::run(_e);
 }
 
-bool CommonSubexpressionEliminator::ExpressionEqual::operator()(Expression const* _a, Expression const* _b) const
+bool CommonSubexpressionEliminator::ExpressionEqual::operator()(Expression const& _a, Expression const& _b) const
 {
-	return SyntacticallyEqual{}(*_a, *_b);
+	return SyntacticallyEqual{}(_a, _b);
 }
diff --git a/libyul/optimiser/CommonSubexpressionEliminator.h b/libyul/optimiser/CommonSubexpressionEliminator.h
index 51e3f886b..f0a42be01 100644
--- a/libyul/optimiser/CommonSubexpressionEliminator.h
+++ b/libyul/optimiser/CommonSubexpressionEliminator.h
@@ -61,14 +61,14 @@ protected:
 	void assignValue(YulString _variable, Expression const* _value) override;
 private:
 	struct ExpressionHash {
-		uint64_t operator()(Expression const*) const;
+		uint64_t operator()(Expression const&) const;
 	};
 	struct ExpressionEqual {
-		bool operator()(Expression const*, Expression const*) const;
+		bool operator()(Expression const&, Expression const&) const;
 	};
 	std::set<YulString> m_returnVariables;
 	std::unordered_map<
-		Expression const*,
+		std::reference_wrapper<Expression const>,
 		std::set<YulString>,
 		ExpressionHash,
 		ExpressionEqual