diff --git a/CHANGELOG b/CHANGELOG
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,5 +1,8 @@
 # Changelog
 
+- 0.2.2 (2025-12-28)
+  * Adds an 'llvm' build flag and tests with GHC 9.10.3.
+
 - 0.2.1 (2025-06-21)
   * Minor performance improvements and internal housekeeping.
 
diff --git a/ppad-base58.cabal b/ppad-base58.cabal
--- a/ppad-base58.cabal
+++ b/ppad-base58.cabal
@@ -1,6 +1,6 @@
 cabal-version:      3.0
 name:               ppad-base58
-version:            0.2.1
+version:            0.2.2
 synopsis:           base58 and base58check encoding/decoding.
 license:            MIT
 license-file:       LICENSE
@@ -8,11 +8,16 @@
 maintainer:         jared@ppad.tech
 category:           Cryptography
 build-type:         Simple
-tested-with:        GHC == 9.8.1
+tested-with:        GHC == 9.10.3
 extra-doc-files:    CHANGELOG
 description:
   base58 and base58check encoding/decoding on strict bytestrings.
 
+flag llvm
+  description: Use GHC's LLVM backend.
+  default:     False
+  manual:      True
+
 source-repository head
   type:     git
   location: git.ppad.tech/base58.git
@@ -22,6 +27,8 @@
   hs-source-dirs:   lib
   ghc-options:
       -Wall
+  if flag(llvm)
+    ghc-options: -fllvm -O2
   exposed-modules:
       Data.ByteString.Base58
     , Data.ByteString.Base58Check
@@ -42,8 +49,8 @@
   build-depends:
       aeson
     , base
-    , base16-bytestring
     , bytestring
+    , ppad-base16
     , ppad-base58
     , tasty
     , tasty-hunit
diff --git a/test/Main.hs b/test/Main.hs
--- a/test/Main.hs
+++ b/test/Main.hs
@@ -21,10 +21,15 @@
   , vc_payload :: !BS.ByteString
   } deriving Show
 
+decodeLenient :: BS.ByteString -> BS.ByteString
+decodeLenient bs = case B16.decode bs of
+  Nothing -> error "boom"
+  Just v -> v
+
 instance A.FromJSON Valid_Base58Check where
   parseJSON = A.withObject "Valid_Base58Check" $ \m -> Valid_Base58Check
     <$> fmap TE.encodeUtf8 (m .: "string")
-    <*> fmap (B16.decodeLenient . TE.encodeUtf8) (m .: "payload")
+    <*> fmap (decodeLenient . TE.encodeUtf8) (m .: "payload")
 
 data Invalid_Base58Check = Invalid_Base58Check {
     ic_string  :: !BS.ByteString
@@ -69,7 +74,7 @@
 
 instance A.FromJSON Valid_Base58 where
   parseJSON = A.withObject "Valid_Base58" $ \m -> Valid_Base58
-    <$> fmap (B16.decodeLenient . TE.encodeUtf8) (m .: "decodedHex")
+    <$> fmap (decodeLenient . TE.encodeUtf8) (m .: "decodedHex")
     <*> fmap TE.encodeUtf8 (m .: "encoded")
 
 execute_base58 :: Valid_Base58 -> TestTree -- XX label