diff --git a/lib/StaticAnalyzer/Checkers/IvarInvalidationChecker.cpp b/lib/StaticAnalyzer/Checkers/IvarInvalidationChecker.cpp
index e269f46..5f94403 100644
--- a/lib/StaticAnalyzer/Checkers/IvarInvalidationChecker.cpp
+++ b/lib/StaticAnalyzer/Checkers/IvarInvalidationChecker.cpp
@@ -111,7 +111,9 @@
     /// The invalidation method being currently processed.
     const ObjCMethodDecl *InvalidationMethod;
 
-    /// Peel off parents, casts, OpaqueValueExpr, and PseudoObjectExpr.
+    ASTContext &Ctx;
+
+    /// Peel off parens, casts, OpaqueValueExpr, and PseudoObjectExpr.
     const Expr *peel(const Expr *E) const;
 
     /// Does this expression represent zero: '0'?
@@ -141,14 +143,16 @@
                   bool &InCalledAnotherInvalidationMethod,
                   const MethToIvarMapTy &InPropertySetterToIvarMap,
                   const MethToIvarMapTy &InPropertyGetterToIvarMap,
-                  const PropToIvarMapTy &InPropertyToIvarMap)
+                  const PropToIvarMapTy &InPropertyToIvarMap,
+                  ASTContext &InCtx)
     : EnclosingMethod(InMeth),
       IVars(InIVars),
       CalledAnotherInvalidationMethod(InCalledAnotherInvalidationMethod),
       PropertySetterToIvarMap(InPropertySetterToIvarMap),
       PropertyGetterToIvarMap(InPropertyGetterToIvarMap),
       PropertyToIvarMap(InPropertyToIvarMap),
-      InvalidationMethod(0) {}
+      InvalidationMethod(0),
+      Ctx(InCtx) {}
 
     void VisitStmt(const Stmt *S) { VisitChildren(S); }
 
@@ -363,7 +367,8 @@
                 CalledAnotherInvalidationMethod,
                 PropSetterToIvarMap,
                 PropGetterToIvarMap,
-                PropertyToIvarMap).VisitStmt(D->getBody());
+                PropertyToIvarMap,
+                BR.getContext()).VisitStmt(D->getBody());
 
   if (CalledAnotherInvalidationMethod)
     return;
@@ -467,21 +472,14 @@
 
 bool IvarInvalidationChecker::MethodCrawler::isZero(const Expr *E) const {
   E = peel(E);
-  if (const IntegerLiteral *IL = dyn_cast<IntegerLiteral>(E))
-    return IL->getValue() == 0;
 
-  if (const CastExpr *ICE = dyn_cast<CastExpr>(E))
-    return ICE->getCastKind() == CK_NullToPointer;
-
-  return false;
+  return (E->isNullPointerConstant(Ctx, Expr::NPC_ValueDependentIsNotNull)
+           != Expr::NPCK_NotNull);
 }
 
 void IvarInvalidationChecker::MethodCrawler::check(const Expr *E) {
   E = peel(E);
 
-  if (const OpaqueValueExpr *OVE = dyn_cast<OpaqueValueExpr>(E))
-    E = OVE->getSourceExpr();
-
   if (const ObjCIvarRefExpr *IvarRef = dyn_cast<ObjCIvarRefExpr>(E)) {
     checkObjCIvarRefExpr(IvarRef);
     return;
@@ -500,7 +498,9 @@
 
 void IvarInvalidationChecker::MethodCrawler::VisitBinaryOperator(
     const BinaryOperator *BO) {
-  if (!BO->isAssignmentOp())
+  VisitStmt(BO);
+
+  if (BO->getOpcode() != BO_Assign)
     return;
 
   // Do we assign zero?
@@ -509,8 +509,6 @@
 
   // Check the variable we are assigning to.
   check(BO->getLHS());
-
-  VisitStmt(BO);
 }
 
 void IvarInvalidationChecker::MethodCrawler::VisitObjCMessageExpr(