diff --git a/tools/bugpoint/ExtractFunction.cpp b/tools/bugpoint/ExtractFunction.cpp
index c03d86ca1fe..e0f9db6d438 100644
--- a/tools/bugpoint/ExtractFunction.cpp
+++ b/tools/bugpoint/ExtractFunction.cpp
@@ -199,7 +199,7 @@ static Constant *GetTorInit(std::vector<std::pair<Function*, int> > &TorList) {
 /// static ctors/dtors, we need to add an llvm.global_[cd]tors global to M2, and
 /// prune appropriate entries out of M1s list.
 static void SplitStaticCtorDtor(const char *GlobalName, Module *M1, Module *M2,
-                                ValueMap<const Value*, Value*> VMap) {
+                                ValueMap<const Value*, Value*> &VMap) {
   GlobalVariable *GV = M1->getNamedGlobal(GlobalName);
   if (!GV || GV->isDeclaration() || GV->hasLocalLinkage() ||
       !GV->use_empty()) return;