diff --git a/synapse/media/v1/base_resource.py b/synapse/media/v1/base_resource.py
index 81f245634..8c62ecd59 100644
--- a/synapse/media/v1/base_resource.py
+++ b/synapse/media/v1/base_resource.py
@@ -93,7 +93,7 @@ class BaseMediaResource(Resource):
         except:
             raise SynapseError(
                 400,
-                "Missing integer argument %r" % (arg_name),
+                "Missing integer argument %r" % (arg_name,),
                 Codes.UNKNOWN,
             )
 
@@ -107,7 +107,7 @@ class BaseMediaResource(Resource):
         except:
             raise SynapseError(
                 400,
-                "Missing string argument %r" % (arg_name),
+                "Missing string argument %r" % (arg_name,),
                 Codes.UNKNOWN,
             )