diff --git a/dev-support/submit-patch.py b/dev-support/submit-patch.py
index 236f31d04ca..577be52472e 100755
--- a/dev-support/submit-patch.py
+++ b/dev-support/submit-patch.py
@@ -250,7 +250,7 @@ patch_filepath = os.path.join(patch_dir, patch_filename)
 
 diff = git.format_patch(base_branch, stdout = True)
 with open(patch_filepath, "w") as f:
-    f.write(diff)
+    f.write(diff.encode('utf8'))
 
 if args.jira_id is not None:
     creds = get_credentials()