diff --git a/requirements.txt b/requirements.txt
index bc3da78..009d622 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -8,5 +8,5 @@ hidapi>=0.7.99.post21
 click>=6.7
 
 # required by link-layer encryption in client.py
-ecdsa
+ecdsa>=0.17
 pyaes
diff --git a/setup.py b/setup.py
index 6eed6c3..ce28efb 100644
--- a/setup.py
+++ b/setup.py
@@ -11,7 +11,7 @@ from setuptools import setup
 
 requirements = [
     'hidapi>=0.7.99.post21',
-    'ecdsa',
+    'ecdsa>=0.17',
     'pyaes',
 ]