1 files changed, 1 insertions, 1 deletions
diff --git a/tests/utils.py b/tests/utils.py
index 8efd3a3475..f15317d27b 100644
--- a/tests/utils.py
+++ b/tests/utils.py
@@ -212,7 +212,7 @@ class MockHttpResource(HttpServer):
 
         headers = {}
         if federation_auth:
-            headers["Authorization"] = ["X-Matrix origin=test,key=,sig="]
+            headers[b"Authorization"] = ["X-Matrix origin=test,key=,sig="]
         mock_request.requestHeaders.getRawHeaders = mock_getRawHeaders(headers)
 
         # return the right path if the event requires it