diff --git a/prusti-server/src/backend.rs b/prusti-server/src/backend.rs
index 9765bd3567e..6841563c2ea 100644
--- a/prusti-server/src/backend.rs
+++ b/prusti-server/src/backend.rs
@@ -39,7 +39,7 @@ impl<'a> Backend<'a> {
                 })
             }
             Backend::Lithium(lithium) => {
-                Stopwatch::start("prusti-server", "vir verification");
+                let _stopwatch = Stopwatch::start("prusti-server", "vir verification");
                 lithium.verify(program)
             }
         }