diff --git a/python/mozbuild/mozbuild/frontend/gyp_reader.py b/python/mozbuild/mozbuild/frontend/gyp_reader.py
index 9fee0c82de82..589609b29053 100644
--- a/python/mozbuild/mozbuild/frontend/gyp_reader.py
+++ b/python/mozbuild/mozbuild/frontend/gyp_reader.py
@@ -251,6 +251,9 @@ def process_gyp_result(gyp_result, gyp_dir_attrs, path, config, output,
             defines = target_conf.get('defines', [])
             if config.substs['CC_TYPE'] == 'clang-cl' and no_chromium:
                 msvs_settings = gyp.msvs_emulation.MsvsSettings(spec, {})
+                # Hack: MsvsSettings._TargetConfig tries to compare a str to an int,
+                # so convert manually.
+                msvs_settings.vs_version.short_name = int(msvs_settings.vs_version.short_name)
                 defines.extend(msvs_settings.GetComputedDefines(c))
             for define in defines:
                 if '=' in define: