diff --git a/requirements.txt b/requirements.txt
index a8d93c94..2f951ac7 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,3 +1,4 @@
+cython
 -e git+git://git.louiz.org/slixmpp#egg=slixmpp
 aiodns
 pygments