diff --git a/youtube_dl/extractor/extractors.py b/youtube_dl/extractor/extractors.py
index 72bc4f57c..5c1d2abfb 100644
--- a/youtube_dl/extractor/extractors.py
+++ b/youtube_dl/extractor/extractors.py
@@ -186,7 +186,10 @@ from .comedycentral import (
 )
 from .comcarcoff import ComCarCoffIE
 from .commonmistakes import CommonMistakesIE, UnicodeBOMIE
-from .commonprotocols import RtmpIE
+from .commonprotocols import (
+    MmsIE,
+    RtmpIE,
+)
 from .condenast import CondeNastIE
 from .cracked import CrackedIE
 from .crackle import CrackleIE