diff --git a/lib/Transforms/Scalar/GVNPRE.cpp b/lib/Transforms/Scalar/GVNPRE.cpp
index 73739c161a9..4a5dca94098 100644
--- a/lib/Transforms/Scalar/GVNPRE.cpp
+++ b/lib/Transforms/Scalar/GVNPRE.cpp
@@ -695,6 +695,7 @@ Value* GVNPRE::find_leader(ValueNumberedSet& vals, uint32_t v) {
     if (v == VN.lookup(*I))
       return *I;
   
+  assert(0 && "No leader found, but present bit is set?");
   return 0;
 }