diff --git a/TreeViz/requirements.txt b/TreeViz/requirements.txt
index e82c1c7..af24d05 100644
--- a/TreeViz/requirements.txt
+++ b/TreeViz/requirements.txt
@@ -28,7 +28,7 @@ decorator==4.0.2
 defer==1.0.6
 dirspec==13.10
 docutils==0.12
-ecdsa==0.13
+ecdsa==0.13.3
 filechunkio==1.6
 funcsigs==0.4
 functools32==3.2.3-2