diff --git a/aqt/addons.py b/aqt/addons.py
index 47279c503..b3a8d6161 100644
--- a/aqt/addons.py
+++ b/aqt/addons.py
@@ -119,7 +119,7 @@ class AddonManager(object):
         if fname.endswith(".py"):
             # .py files go directly into the addon folder
             path = os.path.join(self.addonsFolder(), fname)
-            open(path, "w").write(data)
+            open(path, "wb").write(data)
             return
         # .zip file
         z = ZipFile(StringIO(data))