diff --git a/clang/include/clang/AST/Decl.h b/clang/include/clang/AST/Decl.h
index d124ed2..b464992 100644
--- a/clang/include/clang/AST/Decl.h
+++ b/clang/include/clang/AST/Decl.h
@@ -4589,7 +4589,7 @@
 /// into a diagnostic with <<.
 inline const StreamingDiagnostic &operator<<(const StreamingDiagnostic &PD,
                                              const NamedDecl *ND) {
-  PD.AddTaggedVal(reinterpret_cast<intptr_t>(ND),
+  PD.AddTaggedVal(reinterpret_cast<uint64_t>(ND),
                   DiagnosticsEngine::ak_nameddecl);
   return PD;
 }