diff --git a/requirements.txt b/requirements.txt
index 12eae3a..326f680 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,3 +1,3 @@
 enum34==1.1.2
-ecdsa==0.13
+ecdsa==0.13.3
 pytest==2.9.0
diff --git a/setup.py b/setup.py
index 99ed714..7fccede 100644
--- a/setup.py
+++ b/setup.py
@@ -16,7 +16,7 @@
 
   setup_requires=['pytest-runner'],
   tests_require=['pytest'],
-  install_requires = ['ecdsa==0.13'] + (['enum34==1.0.4'] if sys.version_info < (3, 4) else []),
+  install_requires = ['ecdsa==0.13.3'] + (['enum34==1.0.4'] if sys.version_info < (3, 4) else []),
 
   classifiers = [
       'Development Status :: 4 - Beta',