diff --git a/sim/simflash/src/lib.rs b/sim/simflash/src/lib.rs
index c38baac..6219a85 100644
--- a/sim/simflash/src/lib.rs
+++ b/sim/simflash/src/lib.rs
@@ -186,7 +186,7 @@
             *x = false;
         }
 
-        let mut sub = &mut self.data[offset .. offset + payload.len()];
+        let sub = &mut self.data[offset .. offset + payload.len()];
         sub.copy_from_slice(payload);
         Ok(())
     }