diff --git a/rust/minijail/src/lib.rs b/rust/minijail/src/lib.rs
index cfba237..5028041 100644
--- a/rust/minijail/src/lib.rs
+++ b/rust/minijail/src/lib.rs
@@ -401,7 +401,7 @@
     if ret > 0 && ret <= 0xff {
         return Err(Error::ReturnCode(ret as u8));
     }
-    unreachable!(format!("Unexpected returned value from wait: {}", ret));
+    unreachable!("Unexpected returned value from wait: {}", ret);
 }
 
 impl Minijail {