diff --git a/bitcoin/src/bip32.rs b/bitcoin/src/bip32.rs
index 31d7fce3..a451bf0b 100644
--- a/bitcoin/src/bip32.rs
+++ b/bitcoin/src/bip32.rs
@@ -8,9 +8,9 @@
 
 use core::convert::TryInto;
 use core::default::Default;
-use core::fmt;
 use core::ops::Index;
 use core::str::FromStr;
+use core::{fmt, slice};
 
 use hashes::{hex, sha512, Hash, HashEngine, Hmac, HmacEngine};
 use internals::{impl_array_newtype, write_err};
@@ -209,6 +209,10 @@ impl FromStr for ChildNumber {
     }
 }
 
+impl AsRef<[ChildNumber]> for ChildNumber {
+    fn as_ref(&self) -> &[ChildNumber] { slice::from_ref(self) }
+}
+
 #[cfg(feature = "serde")]
 impl<'de> serde::Deserialize<'de> for ChildNumber {
     fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
@@ -563,7 +567,7 @@ impl ExtendedPrivKey {
     }
 
     /// Private->Private child key derivation
-    pub fn ckd_priv<C: secp256k1::Signing>(
+    fn ckd_priv<C: secp256k1::Signing>(
         &self,
         secp: &Secp256k1<C>,
         i: ChildNumber,