diff --git a/src/mocks.rs b/src/mocks.rs
index fa89b3c..1cf5ecb 100644
--- a/src/mocks.rs
+++ b/src/mocks.rs
@@ -640,7 +640,7 @@ impl MockRouter {
 }
 #[async_trait]
 impl Router for MockRouter {
-    async fn generate_mac(&self, ip: &str, comment: &str) -> anyhow::Result<Option<String>> {
+    async fn generate_mac(&self, ip: &str, comment: &str) -> anyhow::Result<Option<ArpEntry>> {
         Ok(None)
     }