diff --git a/safety-architecture/tools/callgraph-tool/src/lib/VirtualCallTargets.cc b/safety-architecture/tools/callgraph-tool/src/lib/VirtualCallTargets.cc
index 8ffd089..63d220c 100644
--- a/safety-architecture/tools/callgraph-tool/src/lib/VirtualCallTargets.cc
+++ b/safety-architecture/tools/callgraph-tool/src/lib/VirtualCallTargets.cc
@@ -145,7 +145,7 @@ class VirtualCallTargets : public llvm::AnalysisInfoMixin<VirtualCallTargets> {
                 const std::vector<llvm::wholeprogramdevirt::VirtualCallTarget>
                     TargetsForSlot);
 
-  llvm::function_ref<llvm::DominatorTree &(llvm::Function &)> LookupDomTree;
+  std::function<llvm::DominatorTree &(llvm::Function &)> LookupDomTree;
   VTableSlotCallSitesMap CallSlots;
   VirtualCallTargetsResult m_results;
 };