--- a/dom/canvas/test/webgl-conf/generate-wrappers-and-manifest.py
+++ b/dom/canvas/test/webgl-conf/generate-wrappers-and-manifest.py
@@ -526,18 +526,17 @@ def GetFilePathListForDir(baseDir):
             filePath = filePath.replace(os.sep, '/')
             ret.append(filePath)
 
     return ret
 
 
 if __name__ == '__main__':
     file_dir = Path(__file__).parent
-    cwd = Path.cwd()
-    assert cwd.samefile(file_dir), 'Run this file from its directory.'
+    os.chdir(file_dir)
 
     testEntryList = GetTestList()
     wrapperPathStrList = WriteWrappers(testEntryList)
 
     supportPathStrList = GetSupportFileList()
     WriteManifest(wrapperPathStrList, supportPathStrList)
 
     print('Done!')