diff --git a/test/test_youtube_sig.py b/test/test_youtube_sig.py
new file mode 100755
index 000000000..ddd27a9dc
--- /dev/null
+++ b/test/test_youtube_sig.py
@@ -0,0 +1,22 @@
+#!/usr/bin/env python
+
+import unittest
+import sys
+
+# Allow direct execution
+import os
+sys.path.append(os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
+
+from youtube_dl.extractor.youtube import YoutubeIE
+from helper import FakeYDL
+
+sig = YoutubeIE(FakeYDL())._decrypt_signature
+
+class TestYoutubeSig(unittest.TestCase):
+    def test_43_43(self):
+        wrong = '5AEEAE0EC39677BC65FD9021CCD115F1F2DBD5A59E4.C0B243A3E2DED6769199AF3461781E75122AE135135'
+        right = '931EA22157E1871643FA9519676DED253A342B0C.4E95A5DBD2F1F511DCC1209DF56CB77693CE0EAE'
+        self.assertEqual(sig(wrong), right)
+
+if __name__ == '__main__':
+    unittest.main()