diff --git a/requirements.txt b/requirements.txt
index 3ae8b803..8a0e7b56 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,3 +1,3 @@
 ufoLib==2.1.1
-defcon==0.3.5
+defcon==0.5.1
 fontMath==0.4.4