diff --git a/mautrix/__init__.py b/mautrix/__init__.py
index ce7df73a..455409e9 100644
--- a/mautrix/__init__.py
+++ b/mautrix/__init__.py
@@ -1,4 +1,4 @@
-__version__ = "0.19.15"
+__version__ = "0.19.16"
 __author__ = "Tulir Asokan <tulir@maunium.net>"
 __all__ = [
     "api",
diff --git a/mautrix/appservice/as_handler.py b/mautrix/appservice/as_handler.py
index b49a8583..9d5ad20a 100644
--- a/mautrix/appservice/as_handler.py
+++ b/mautrix/appservice/as_handler.py
@@ -83,7 +83,9 @@ def _check_token(self, request: web.Request) -> bool:
             token = request.rel_url.query["access_token"]
         except KeyError:
             try:
-                token = request.headers["Authorization"].removeprefix("Bearer ")
+                token = request.headers["Authorization"]
+                if token.startswith("Bearer "):
+                    token = token[len("Bearer "):]
             except (KeyError, AttributeError):
                 self.log.trace("No access_token nor Authorization header in request")
                 return False