diff --git a/src/dawn/tests/BUILD.gn b/src/dawn/tests/BUILD.gn
index bfeb26a930..35e216558e 100644
--- a/src/dawn/tests/BUILD.gn
+++ b/src/dawn/tests/BUILD.gn
@@ -132,6 +132,7 @@ if (build_with_chromium && is_win &&
   assert(defined(windows_sdk_path))
   assert(defined(windows_sdk_version))
   assert(windows_sdk_path != "")
+  assert(windows_sdk_version != "")
 
   # Declare a copy target to copy DXC binary from Windows SDK for running Dawn
   # end-to-end test in Chromium.