diff --git a/vm_supervisor/views.py b/vm_supervisor/views.py
index 28146f530..3d6ddb4a9 100644
--- a/vm_supervisor/views.py
+++ b/vm_supervisor/views.py
@@ -174,7 +174,7 @@ async def status_check_version(request: web.Request):
 def authenticate_api_request(request: web.Request) -> bool:
     """Authenticate an API request to update the VM allocations.
     """
-    signature: str = request.headers.get('X-Auth-Signature')
+    signature: bytes = request.headers.get('X-Auth-Signature').encode()
     # body: bytes = await request.read()
     if not signature:
         raise web.HTTPUnauthorized(text="Authentication token is missing")