diff --git a/synapse/config/server.py b/synapse/config/server.py
index d9d8d0e14e..9332e4acd7 100644
--- a/synapse/config/server.py
+++ b/synapse/config/server.py
@@ -94,7 +94,7 @@ class ServerConfig(Config):
             with open(args.signing_key_path, "w") as signing_key_file:
                 syutil.crypto.signing_key.write_signing_keys(
                     signing_key_file,
-                    (syutil.crypto.SigningKey.generate("auto"),),
+                    (syutil.crypto.signing_key.generate_singing_key("auto"),),
                 )
         else:
             signing_keys = cls.read_file(args.signing_key_path, "signing_key")