diff --git a/CHANGELOG b/CHANGELOG
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,5 +1,9 @@
 # Changelog
 
+- 0.2.1 (2025-02-24)
+  * Merely swaps out the base16 library used for the Wycheproof tests
+    (in favour of ppad-base16).
+
 - 0.2.0 (2025-01-10)
   * API change, opting for "derive" in place of "hkdf" to work more
     smoothly with a import qualifier like "KDF".
diff --git a/lib/Crypto/KDF/HMAC.hs b/lib/Crypto/KDF/HMAC.hs
--- a/lib/Crypto/KDF/HMAC.hs
+++ b/lib/Crypto/KDF/HMAC.hs
@@ -12,9 +12,11 @@
 -- [RFC5869](https://datatracker.ietf.org/doc/html/rfc5869).
 
 module Crypto.KDF.HMAC (
+    -- * HMAC synonym
+    HMAC
+
     -- * HMAC-based KDF
-    derive
-  , HMAC
+  , derive
 
     -- internals
   , extract
@@ -40,6 +42,8 @@
 --   >>> import qualified Crypto.Hash.SHA256 as SHA256
 --   >>> :t SHA256.hmac
 --   SHA256.hmac :: BS.ByteString -> BS.ByteString -> BS.ByteString
+--   >>> SHA256.hmac "my HMAC key" "my HMAC input"
+--   <256-bit MAC>
 type HMAC = BS.ByteString -> BS.ByteString -> BS.ByteString
 
 -- HMAC function and its associated outlength
diff --git a/ppad-hkdf.cabal b/ppad-hkdf.cabal
--- a/ppad-hkdf.cabal
+++ b/ppad-hkdf.cabal
@@ -1,6 +1,6 @@
 cabal-version:      3.0
 name:               ppad-hkdf
-version:            0.2.0
+version:            0.2.1
 synopsis:           A HMAC-based key derivation function
 license:            MIT
 license-file:       LICENSE
@@ -43,8 +43,8 @@
   build-depends:
       aeson
     , base
-    , base16-bytestring
     , bytestring
+    , ppad-base16
     , ppad-hkdf
     , ppad-sha256
     , ppad-sha512
diff --git a/test/Wycheproof.hs b/test/Wycheproof.hs
--- a/test/Wycheproof.hs
+++ b/test/Wycheproof.hs
@@ -48,7 +48,9 @@
   } deriving Show
 
 decodehex :: T.Text -> BS.ByteString
-decodehex = B16.decodeLenient . TE.encodeUtf8
+decodehex t = case B16.decode (TE.encodeUtf8 t) of
+  Nothing -> error "bang"
+  Just bs -> bs
 
 instance A.FromJSON HkdfTest where
   parseJSON = A.withObject "HkdfTest" $ \m -> HkdfTest