diff --git a/libyul/optimiser/KnowledgeBase.cpp b/libyul/optimiser/KnowledgeBase.cpp
index 36f07b74a..4b90acf9f 100644
--- a/libyul/optimiser/KnowledgeBase.cpp
+++ b/libyul/optimiser/KnowledgeBase.cpp
@@ -117,9 +117,9 @@ KnowledgeBase::VariableOffset KnowledgeBase::explore(YulString _var)
 
 optional<KnowledgeBase::VariableOffset> KnowledgeBase::explore(Expression const& _value)
 {
-	if (Literal const* literal = std::get_if<Literal>(&_value))
+	if (Literal const* literal = get_if<Literal>(&_value))
 		return VariableOffset{YulString{}, valueOfLiteral(*literal)};
-	else if (Identifier const* identifier = std::get_if<Identifier>(&_value))
+	else if (Identifier const* identifier = get_if<Identifier>(&_value))
 		return explore(identifier->name);
 	else if (FunctionCall const* f = get_if<FunctionCall>(&_value))
 	{