diff --git a/piecrust/src/imports.rs b/piecrust/src/imports.rs
index aae5d8e0..4c375143 100644
--- a/piecrust/src/imports.rs
+++ b/piecrust/src/imports.rs
@@ -230,7 +230,7 @@ pub(crate) fn c(
 
     let with_memory = |memory: &mut [u8]| -> Result<_, Error> {
         let arg_buf = &memory[argbuf_ofs..][..ARGBUF_LEN];
-        let arg_buf_b = &memory[argbuf_b_ofs..][..ARGBUF_B_LEN as usize];
+        let arg_buf_b = &memory[argbuf_b_ofs..][..ARGBUF_B_LEN];
 
         let mut mod_id = ContractId::uninitialized();
         mod_id.as_bytes_mut().copy_from_slice(
@@ -252,7 +252,7 @@ pub(crate) fn c(
         let name = core::str::from_utf8(&memory[name_ofs..][..name_len])?;
 
         let arg = &arg_buf[..arg_len as usize];
-        let arg_b = &arg_buf_b[..ARGBUF_B_LEN as usize];
+        let arg_b = &arg_buf_b[..ARGBUF_B_LEN];
 
         callee.write_argument(arg);
         callee.write_argument_b(arg_b);
@@ -263,9 +263,7 @@ pub(crate) fn c(
 
         // copy back result
         callee.read_argument(&mut memory[argbuf_ofs..][..ret_len as usize]);
-        callee.read_argument_b(
-            &mut memory[argbuf_b_ofs..][..ARGBUF_B_LEN as usize],
-        );
+        callee.read_argument_b(&mut memory[argbuf_b_ofs..][..ARGBUF_B_LEN]);
 
         let callee_remaining = callee.get_remaining_gas();
         let callee_spent = callee_limit - callee_remaining;