diff --git a/lib/Analysis/GRExprEngine.cpp b/lib/Analysis/GRExprEngine.cpp
index 7dbb085..528a469 100644
--- a/lib/Analysis/GRExprEngine.cpp
+++ b/lib/Analysis/GRExprEngine.cpp
@@ -2841,7 +2841,7 @@
 //===----------------------------------------------------------------------===//
 
 Checker *GRExprEngine::lookupChecker(void *tag) const {
-  CheckerMap::iterator I = CheckerM.find(tag);
+  CheckerMap::const_iterator I = CheckerM.find(tag);
   return (I == CheckerM.end()) ? NULL : Checkers[I->second].second;
 }