diff --git a/shake256-33bytes-demo/methods/guest/src/main.rs b/shake256-33bytes-demo/methods/guest/src/main.rs
index e92b286..61195de 100644
--- a/shake256-33bytes-demo/methods/guest/src/main.rs
+++ b/shake256-33bytes-demo/methods/guest/src/main.rs
@@ -70,7 +70,7 @@ mod crypto {
         out_index: u32,
     ) -> [u8; 32] {
         let mut hasher = Sha256::new();
-        sha2::Digest::update(&mut hasher, b"NSSA/v0.1/KDF-SHA256");
+        hasher.update( b"NSSA/v0.1/KDF-SHA256");
         sha2::Digest::update(&mut hasher, &ss_bytes);
         sha2::Digest::update(&mut hasher, &epk[..]);
         sha2::Digest::update(&mut hasher, &ipk[..]);