diff --git a/requirements.txt b/requirements.txt
index 2f87569..a217676 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,4 +1,5 @@
-flask>=0.9
+flask==0.9
+werkzeug==0.8.3
 numpy>=1.6.2
 pyserial>=2.6
 tornado>=2.4.1