diff --git a/bower.json b/bower.json
index 24c940d..ffc1c9c 100644
--- a/bower.json
+++ b/bower.json
@@ -12,9 +12,9 @@
     "output"
   ],
   "dependencies": {
-    "purescript-prelude": "^3.1.0",
-    "purescript-foreign-generic": "^5.0.0",
-    "purescript-typelevel-prelude": "^2.6.0",
+    "purescript-prelude": "^3.3.0",
+    "purescript-foreign-generic": "^6.0.0",
+    "purescript-typelevel-prelude": "^2.7.0",
     "purescript-record": "^0.2.6",
     "purescript-nullable": "^3.0.0",
     "purescript-variant": "^4.1.0"
diff --git a/src/Simple/JSON.purs b/src/Simple/JSON.purs
index 1baeb06..a2e8a34 100644
--- a/src/Simple/JSON.purs
+++ b/src/Simple/JSON.purs
@@ -31,8 +31,8 @@ import Data.Foreign (F, Foreign, ForeignError(..), MultipleErrors, fail, readArr
 import Data.Foreign.Index (readProp)
 import Data.Foreign.Internal (readStrMap)
 import Data.Foreign.JSON (parseJSON)
-import Data.Foreign.NullOrUndefined (NullOrUndefined(NullOrUndefined), readNullOrUndefined, unNullOrUndefined, undefined)
-import Data.Maybe (Maybe(..), maybe)
+import Data.Foreign.NullOrUndefined (readNullOrUndefined, undefined)
+import Data.Maybe (Maybe(Nothing), maybe)
 import Data.Nullable (Nullable, toMaybe, toNullable)
 import Data.Record (get)
 import Data.Record.Builder (Builder)
@@ -110,11 +110,8 @@ instance readBoolean :: ReadForeign Boolean where
 instance readArray :: ReadForeign a => ReadForeign (Array a) where
   readImpl = traverse readImpl <=< readArray
 
-instance readNullOrUndefined :: ReadForeign a => ReadForeign (NullOrUndefined a) where
-  readImpl = readNullOrUndefined readImpl
-
 instance readMaybe :: ReadForeign a => ReadForeign (Maybe a) where
-  readImpl = map unNullOrUndefined <<< readImpl
+  readImpl = readNullOrUndefined readImpl
 
 instance readNullable :: ReadForeign a => ReadForeign (Nullable a) where
   readImpl o = withExcept (map reformat) $
@@ -230,15 +227,11 @@ instance writeForeignBoolean :: WriteForeign Boolean where
 instance writeForeignArray :: WriteForeign a => WriteForeign (Array a) where
   writeImpl xs = toForeign $ writeImpl <$> xs
 
-instance writeForeignNullOrUndefined :: WriteForeign a => WriteForeign (NullOrUndefined a) where
-  writeImpl (NullOrUndefined a) = maybe undefined writeImpl a
-
 instance writeForeignMaybe :: WriteForeign a => WriteForeign (Maybe a) where
-  writeImpl (Just a) = writeImpl a
-  writeImpl Nothing = toForeign $ toNullable Nothing
+  writeImpl = maybe undefined writeImpl
 
 instance writeForeignNullable :: WriteForeign a => WriteForeign (Nullable a) where
-  writeImpl = writeImpl <<< toMaybe
+  writeImpl = maybe (toForeign $ toNullable Nothing) writeImpl <<< toMaybe
 
 instance writeForeignStrMap :: WriteForeign a => WriteForeign (StrMap.StrMap a) where
   writeImpl = toForeign <<< StrMap.mapWithKey (const writeImpl)
diff --git a/test/Main.purs b/test/Main.purs
index cd05209..8757a51 100644
--- a/test/Main.purs
+++ b/test/Main.purs
@@ -8,7 +8,6 @@ import Data.Argonaut.Core (Json)
 import Data.Argonaut.Parser (jsonParser)
 import Data.Either (Either(..), either, fromLeft, isRight)
 import Data.Foreign (ForeignError(..), MultipleErrors)
-import Data.Foreign.NullOrUndefined (NullOrUndefined)
 import Data.List (List(..))
 import Data.List.NonEmpty (NonEmptyList(..))
 import Data.Maybe (Maybe)
@@ -38,7 +37,7 @@ type MyTestNull =
   , b :: String
   , c :: Boolean
   , d :: Array String
-  , e :: NullOrUndefined (Array String)
+  , e :: Maybe (Array String)
   }
 
 type MyTestStrMap =
@@ -102,7 +101,7 @@ main = run [consoleReporter] do
 
     it "works with missing Maybe fields by setting them to Nothing" do
       let result = readJSON "{}"
-      (writeJSON <$> (result :: E MyTestMaybe)) `shouldEqual` (Right """{"a":null}""")
+      (writeJSON <$> (result :: E MyTestMaybe)) `shouldEqual` (Right """{}""")
 
     it "fails with undefined for null with correct error message" do
       let result = readJSON """
@@ -116,10 +115,10 @@ main = run [consoleReporter] do
     it "works with proper JSON" $ roundtrips (Proxy :: Proxy MyTest) """
         { "a": 1, "b": "asdf", "c": true, "d": ["A", "B"]}
       """
-    it "works with JSON lacking NullOrUndefined field" $ roundtrips (Proxy :: Proxy MyTestNull) """
+    it "works with JSON lacking Maybe field" $ roundtrips (Proxy :: Proxy MyTestNull) """
         { "a": 1, "b": "asdf", "c": true, "d": ["A", "B"]}
       """
-    it "works with JSON containing NullOrUndefined field" $ roundtrips (Proxy :: Proxy MyTestNull) """
+    it "works with JSON containing Maybe field" $ roundtrips (Proxy :: Proxy MyTestNull) """
         { "a": 1, "b": "asdf", "c": true, "d": ["A", "B"], "e": ["C", "D"]}
       """
     it "works with JSON containing StrMap field" $ roundtrips (Proxy :: Proxy MyTestStrMap) """
@@ -128,12 +127,6 @@ main = run [consoleReporter] do
     it "works with Maybe field and existing value" $ roundtrips (Proxy :: Proxy MyTestMaybe) """
         { "a": "foo" }
       """
-    it "works with Maybe field and null value" $ roundtrips (Proxy :: Proxy MyTestMaybe) """
-        { "a": null }
-      """
-    it "works with many Maybe fields" $ roundtrips (Proxy :: Proxy MyTestManyMaybe) """
-      { "a": "str", "aNull": null, "b":1, "bNull": null, "c":true, "cNull":null, "d":1.1, "dNull":null, "e":["str1", "str2", null], "eNull": null }
-    """
     it "works with Nullable" $ roundtrips (Proxy :: Proxy MyTestNullable) """
       { "a": null, "b": "a" }
     """