diff --git a/requirements.txt b/requirements.txt
index d77d77b..6eadd74 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1 +1,3 @@
 Twisted>=12.0.0
+https://pypi.python.org/packages/source/b/bitstring/bitstring-3.1.3.zip
+