diff --git a/hashes/src/util.rs b/hashes/src/util.rs
index 0d2b8cb2b..8cbf4b180 100644
--- a/hashes/src/util.rs
+++ b/hashes/src/util.rs
@@ -91,7 +91,7 @@ macro_rules! engine_input_impl(
             for c in inp {
                 self.buffer[0] ^= *c;
             }
-            self.bytes_hashed += inp.len();
+            self.bytes_hashed += inp.len() as u64;
         }
     )
 );