diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,8 +1,15 @@
 # Changelog
 
+## [0.1.0.1] - 2022-05-03
+
+### Changed
+
+* Generalised the type of `parseAlternative`.
+
 ## [0.1.0.0] - 2022-05-03
 
 ### Changed
+
 * Generalise type of `matchChoiceCodec` to allow for two different input types.
 * Add disjoint versions of `matchChoiceCodec` and `matchChoicesCodec`.
 * Functions `enumCodec`, `stringConstCodec`, and `shownBoundedEnumCodec` now produce disjoint codecs.
diff --git a/autodocodec.cabal b/autodocodec.cabal
--- a/autodocodec.cabal
+++ b/autodocodec.cabal
@@ -5,7 +5,7 @@
 -- see: https://github.com/sol/hpack
 
 name:           autodocodec
-version:        0.1.0.0
+version:        0.1.0.1
 synopsis:       Self-documenting encoder and decoder
 homepage:       https://github.com/NorfairKing/autodocodec#readme
 bug-reports:    https://github.com/NorfairKing/autodocodec/issues
diff --git a/src/Autodocodec/Codec.hs b/src/Autodocodec/Codec.hs
--- a/src/Autodocodec/Codec.hs
+++ b/src/Autodocodec/Codec.hs
@@ -1514,9 +1514,9 @@
   -- | Main codec, for parsing and rendering
   Codec context input output ->
   -- | Alternative codecs just for parsing
-  Codec context input output ->
+  Codec context input' output ->
   Codec context input output
-parseAlternative c cAlt = parseAlternatives c [cAlt]
+parseAlternative c cAlt = matchChoiceCodec c cAlt Left
 
 -- | A codec for an enum that can be written each with their own codec.
 --