diff --git a/requirements.txt b/requirements.txt
index 94d5fc3..3d17f78 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,3 +1,3 @@
-ecdsa==0.13 --hash=sha256:40d002cf360d0e035cf2cb985e1308d41aaa087cbfc135b2dc2d844296ea546c
+ecdsa==0.13.3 --hash=sha256:9814e700890991abeceeb2242586024d4758c8fc18445b194a49bd62d85861db --hash=sha256:163c80b064a763ea733870feb96f9dd9b92216cfcacd374837af18e4e8ec3d4d
 python-bitcoinlib==0.7.0 --hash=sha256:a083f61b30c7d748f8c785591fbdc26dbad98b64946cd1fbbf25c860b8ff7c3c
 enum34==1.1.6; python_version < '3.4'