diff --git a/tools/clang/lib/Sema/SemaHLSL.cpp b/tools/clang/lib/Sema/SemaHLSL.cpp
index d831f51f09..f73a4d96bb 100644
--- a/tools/clang/lib/Sema/SemaHLSL.cpp
+++ b/tools/clang/lib/Sema/SemaHLSL.cpp
@@ -13134,7 +13134,7 @@ void Sema::DiagnoseGloballyCoherentMismatch(const Expr *SrcExpr,
 
 void ValidateDispatchGridValues(DiagnosticsEngine &Diags,
                                 const AttributeList &A, Attr *declAttr) {
-  unsigned x = 1, y = 1, z = 1;
+  unsigned long long int x = 1, y = 1, z = 1;
   if (HLSLNodeDispatchGridAttr *pA =
           dyn_cast<HLSLNodeDispatchGridAttr>(declAttr)) {
     x = pA->getX();
diff --git a/tools/clang/test/SemaHLSL/attributes/overflow_node_dispatch_grid.hlsl b/tools/clang/test/SemaHLSL/attributes/overflow_node_dispatch_grid.hlsl
new file mode 100644
index 0000000000..767ed72a74
--- /dev/null
+++ b/tools/clang/test/SemaHLSL/attributes/overflow_node_dispatch_grid.hlsl
@@ -0,0 +1,7 @@
+// RUN: %dxc -T lib_6_8 -verify %s
+
+[Shader("node")]
+[NodeLaunch("broadcasting")]
+[NodeDispatchGrid(65535, 65535, 65535)] // expected-error {{'NodeDispatchGrid' X * Y * Z product may not exceed 16,777,215 (2^24-1)}}
+[NumThreads(1, 1, 1)]
+void myNode() { }
\ No newline at end of file