diff --git a/include/clang/StaticAnalyzer/Core/PathSensitive/CoreEngine.h b/include/clang/StaticAnalyzer/Core/PathSensitive/CoreEngine.h
index 59136fc314..f5984021d8 100644
--- a/include/clang/StaticAnalyzer/Core/PathSensitive/CoreEngine.h
+++ b/include/clang/StaticAnalyzer/Core/PathSensitive/CoreEngine.h
@@ -188,10 +188,10 @@ public:
 
 // TODO: Turn into a calss.
 struct NodeBuilderContext {
-  CoreEngine &Eng;
+  const CoreEngine &Eng;
   const CFGBlock *Block;
   ExplodedNode *Pred;
-  NodeBuilderContext(CoreEngine &E, const CFGBlock *B, ExplodedNode *N)
+  NodeBuilderContext(const CoreEngine &E, const CFGBlock *B, ExplodedNode *N)
     : Eng(E), Block(B), Pred(N) { assert(B); assert(!N->isSink()); }
 
   ExplodedNode *getPred() const { return Pred; }