diff --git a/dockerfiles/oj_web_server/requirements.txt b/dockerfiles/oj_web_server/requirements.txt
index a6cf75f..7ad8718 100644
--- a/dockerfiles/oj_web_server/requirements.txt
+++ b/dockerfiles/oj_web_server/requirements.txt
@@ -10,4 +10,5 @@ coverage
 django-extensions
 supervisor
 pillow
-jsonfield
\ No newline at end of file
+jsonfield
+Envelopes
\ No newline at end of file