diff --git a/sim/src/api.rs b/sim/src/api.rs
index 71d4643..ec502a2 100644
--- a/sim/src/api.rs
+++ b/sim/src/api.rs
@@ -29,6 +29,9 @@
 fn map_err(err: Result<()>) -> libc::c_int {
     match err {
         Ok(()) => 0,
-        Err(_) => -1,
+        Err(e) => {
+            warn!("{}", e);
+            -1
+        },
     }
 }