diff --git a/session/session.go b/session/session.go
index 908b7f37..af8c47bc 100644
--- a/session/session.go
+++ b/session/session.go
@@ -334,7 +334,7 @@ func (manager *Manager) sessionID() (string, error) {
 	}
 	sid := hex.EncodeToString(b)
 	if manager.config.SessionIDPrefix != "" {
-		return manager.config.SessionIDPrefix + sid
+		return manager.config.SessionIDPrefix + sid, nil
 	}
 	return sid, nil
 }