diff --git a/lib/Transforms/Vectorize/BBVectorize.cpp b/lib/Transforms/Vectorize/BBVectorize.cpp
index 7d5bb31401c..82be6971bd1 100644
--- a/lib/Transforms/Vectorize/BBVectorize.cpp
+++ b/lib/Transforms/Vectorize/BBVectorize.cpp
@@ -141,7 +141,7 @@ namespace {
   struct BBVectorize : public BasicBlockPass {
     static char ID; // Pass identification, replacement for typeid
 
-    VectorizeConfig Config;
+    const VectorizeConfig Config;
 
     BBVectorize(const VectorizeConfig &C = VectorizeConfig())
       : BasicBlockPass(ID), Config(C) {