diff --git a/youtube_dl/extractor/youtube.py b/youtube_dl/extractor/youtube.py
index 64a3e39c1..bf064c181 100644
--- a/youtube_dl/extractor/youtube.py
+++ b/youtube_dl/extractor/youtube.py
@@ -340,7 +340,7 @@ def _decrypt_signature(self, s):
         elif len(s) == 88:
             return s[48] + s[81:67:-1] + s[82] + s[66:62:-1] + s[85] + s[61:48:-1] + s[67] + s[47:12:-1] + s[3] + s[11:3:-1] + s[2] + s[12]
         elif len(s) == 87:
-            return s[83:53:-1] + s[3] + s[52:40:-1] + s[86] + s[39:10:-1] + s[0] + s[9:3:-1] + s[53]
+            return s[6:27] + s[4] + s[28:39] + s[27] + s[40:59] + s[2] + s[60:]
         elif len(s) == 86:
             return s[5:20] + s[2] + s[21:]
         elif len(s) == 85: