diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,10 @@
 # Changelog
 
+## [0.0.1.2] - 2024-08-20
+
+* Fixed the nix type that corresponds to `null`.
+* Fixed that some nix types were not being simplified enough.
+
 ## [0.0.1.1] - 2024-08-20
 
 ### Changed
diff --git a/autodocodec-nix.cabal b/autodocodec-nix.cabal
--- a/autodocodec-nix.cabal
+++ b/autodocodec-nix.cabal
@@ -5,7 +5,7 @@
 -- see: https://github.com/sol/hpack
 
 name:           autodocodec-nix
-version:        0.0.1.1
+version:        0.0.1.2
 synopsis:       Autodocodec interpreters for nix
 homepage:       https://github.com/NorfairKing/autodocodec#readme
 bug-reports:    https://github.com/NorfairKing/autodocodec/issues
diff --git a/src/Autodocodec/Nix.hs b/src/Autodocodec/Nix.hs
--- a/src/Autodocodec/Nix.hs
+++ b/src/Autodocodec/Nix.hs
@@ -209,7 +209,12 @@
       OptionTypeAttrsOf o -> OptionTypeAttrsOf $ go o
       OptionTypeOneOf os -> case goEnums $ nubOrd $ concatMap goOr os of
         [ot] -> ot
-        os' -> OptionTypeOneOf os'
+        os' ->
+          if OptionTypeNull `elem` os'
+            then go $ OptionTypeNullOr $ case filter (/= OptionTypeNull) os' of
+              [t] -> t
+              ts' -> OptionTypeOneOf ts'
+            else OptionTypeOneOf os'
       OptionTypeSubmodule m -> OptionTypeSubmodule $ M.map goOpt m
 
     goEnums :: [OptionType] -> [OptionType]
@@ -270,7 +275,7 @@
 optionTypeExpr = go
   where
     go = \case
-      OptionTypeNull -> ExprVar "lib.types.null"
+      OptionTypeNull -> ExprAp (ExprVar "lib.types.enum") (ExprLitList [ExprNull])
       OptionTypeSimple s -> ExprVar s
       OptionTypeEnum es -> ExprAp (ExprVar "lib.types.enum") (ExprLitList es)
       OptionTypeNullOr ot -> ExprAp (ExprVar "lib.types.nullOr") (go ot)