diff --git a/requirements.txt b/requirements.txt
index 8d6199b..a9a4d76 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,3 +1,3 @@
 base58==0.2.5
-ecdsa==0.13
+ecdsa==0.13.3
 docopt==0.6.2