diff --git a/lib/Checker/ObjCAtSyncChecker.cpp b/lib/Checker/ObjCAtSyncChecker.cpp
index 139cac2..62428d2 100644
--- a/lib/Checker/ObjCAtSyncChecker.cpp
+++ b/lib/Checker/ObjCAtSyncChecker.cpp
@@ -64,7 +64,7 @@
 
   // Check for null mutexes.
   const GRState *notNullState, *nullState;
-  llvm::tie(notNullState, nullState) = state->Assume(cast<DefinedSVal>(V));
+  llvm::tie(notNullState, nullState) = state->assume(cast<DefinedSVal>(V));
 
   if (nullState) {
     if (!notNullState) {