diff --git a/index.py b/index.py
index 9ebe0e6..5784742 100644
--- a/index.py
+++ b/index.py
@@ -90,7 +90,7 @@ def index():
                 if type(key) == unicode:
                     key = key.encode()
                 mac = hmac.new(key, msg=request.data, digestmod=sha1)
-                if not compare_digest(mac.hexdigest(), signature):
+                if not compare_digest(mac.hexdigest(), str(signature)):
                     abort(403)
 
         if repo.get('action', None):