diff --git a/src/ratchet.rs b/src/ratchet.rs
index 2015f30..67435c8 100644
--- a/src/ratchet.rs
+++ b/src/ratchet.rs
@@ -375,7 +375,7 @@ impl RatchetEncHeader {
         }
         if let Some(d) = &mut self.ckr {
             while self.nr < until {
-                let (ckr, mk) = kdf_ck(&d);
+                let (ckr, mk) = kdf_ck(d);
                 *d = ckr;
                 self.mkskipped.insert((self.hkr, self.nr), mk);
                 self.nr += 1