diff --git a/lib/CodeGen/CGObjC.cpp b/lib/CodeGen/CGObjC.cpp
index cf1ff23..0118537 100644
--- a/lib/CodeGen/CGObjC.cpp
+++ b/lib/CodeGen/CGObjC.cpp
@@ -236,7 +236,8 @@
     CallArgList Args;
     Args.push_back(std::make_pair(RValue::get(SelfAsId), IdTy));
     Args.push_back(std::make_pair(RValue::get(CmdVal), Cmd->getType()));
-    Args.push_back(std::make_pair(RValue::get(Offset), getContext().LongTy));
+    Args.push_back(std::make_pair(RValue::get(Offset),
+                getContext().getPointerDiffType()));
     Args.push_back(std::make_pair(RValue::get(True), getContext().BoolTy));
     // FIXME: We shouldn't need to get the function info here, the
     // runtime already should have computed it to build the function.
@@ -394,7 +395,8 @@
     CallArgList Args;
     Args.push_back(std::make_pair(RValue::get(SelfAsId), IdTy));
     Args.push_back(std::make_pair(RValue::get(CmdVal), Cmd->getType()));
-    Args.push_back(std::make_pair(RValue::get(Offset), getContext().LongTy));
+    Args.push_back(std::make_pair(RValue::get(Offset),
+                getContext().getPointerDiffType()));
     Args.push_back(std::make_pair(RValue::get(ArgAsId), IdTy));
     Args.push_back(std::make_pair(RValue::get(IsAtomic ? True : False),
                                   getContext().BoolTy));
diff --git a/lib/CodeGen/CGObjCMac.cpp b/lib/CodeGen/CGObjCMac.cpp
index a33e094..1900a85 100644
--- a/lib/CodeGen/CGObjCMac.cpp
+++ b/lib/CodeGen/CGObjCMac.cpp
@@ -328,7 +328,7 @@
     CanQualType SelType = Ctx.getCanonicalParamType(Ctx.getObjCSelType());
     Params.push_back(IdType);
     Params.push_back(SelType);
-    Params.push_back(Ctx.LongTy);
+    Params.push_back(Ctx.getPointerDiffType()->getCanonicalTypeUnqualified());
     Params.push_back(Ctx.BoolTy);
     const llvm::FunctionType *FTy =
       Types.GetFunctionType(Types.getFunctionInfo(IdType, Params,
@@ -346,7 +346,7 @@
     CanQualType SelType = Ctx.getCanonicalParamType(Ctx.getObjCSelType());
     Params.push_back(IdType);
     Params.push_back(SelType);
-    Params.push_back(Ctx.LongTy);
+    Params.push_back(Ctx.getPointerDiffType()->getCanonicalTypeUnqualified());
     Params.push_back(IdType);
     Params.push_back(Ctx.BoolTy);
     Params.push_back(Ctx.BoolTy);