diff --git a/libyul/ControlFlowSideEffectsCollector.cpp b/libyul/ControlFlowSideEffectsCollector.cpp
index 047480f14..f907f83f5 100644
--- a/libyul/ControlFlowSideEffectsCollector.cpp
+++ b/libyul/ControlFlowSideEffectsCollector.cpp
@@ -212,7 +212,8 @@ ControlFlowSideEffectsCollector::ControlFlowSideEffectsCollector(
 			if (calledSideEffects->canRevert)
 				sideEffects.canRevert = true;
 
-			for (YulString callee: util::valueOrDefault(m_functionCalls, _function))
+			set<YulString> emptySet;
+			for (YulString callee: util::valueOrDefault(m_functionCalls, _function, emptySet))
 				_recurse(callee, _recurse);
 		};
 		for (auto const& call: calls)