diff --git a/package.yaml b/package.yaml
index f6adcf3..25388df 100644
--- a/package.yaml
+++ b/package.yaml
@@ -21,13 +21,12 @@ description:         Please see the README on Github at
 
 dependencies:
   - base >= 4.7 && < 5
-  - bytestring >= 0.9 && <= 0.10.8.2
-  - exceptions >= 0.8 && <= 0.8.3
-  - free >= 4.0 && <= 4.12.4
-  - ghc-prim >= 0.5.0.0 && <= 0.5.1.1
-  - mtl >= 2.0.0.0 && <= 2.2.1
-  - text >= 1.2.0.0 && <= 1.2.2.2
-  - transformers >= 0.5.2.0 && <= 0.5.5.0
+  - bytestring >= 0.9 && <= 0.11
+  - exceptions >= 0.8 && <= 0.9
+  - free >= 4 && <= 5
+  - mtl >= 2 && <= 2.2.1
+  - text >= 1.2 && <= 1.2.2.2
+  - transformers >= 0.5.2 && <= 0.5.5
 
 library:
   source-dirs: src
diff --git a/postlude.cabal b/postlude.cabal
index 5567af9..24de3f1 100644
--- a/postlude.cabal
+++ b/postlude.cabal
@@ -2,7 +2,7 @@
 --
 -- see: https://github.com/sol/hpack
 --
--- hash: a0f8ab1c4a70737a18ce50a346d1cdc193d7ff1f4e1b2114f1ea82f8ca03d9b2
+-- hash: 11b8c26f553bf674da8af0841f67c273e62a36110eb4ff1dde16718067ba7f1a
 
 name:           postlude
 version:        0.1.0.1
@@ -28,14 +28,13 @@ library
   hs-source-dirs:
       src
   build-depends:
-      base >=4.7 && <5
-    , bytestring >=0.9 && <=0.10.8.2
-    , exceptions >=0.8 && <=0.8.3
-    , free >=4.0 && <=4.12.4
-    , ghc-prim >=0.5.0.0 && <=0.5.1.1
-    , mtl >=2.0.0.0 && <=2.2.1
-    , text >=1.2.0.0 && <=1.2.2.2
-    , transformers >=0.5.2.0 && <=0.5.5.0
+      base >=4.10.1.0 && <5
+    , bytestring >=0.9 && <=0.11
+    , exceptions >=0.8 && <=0.9
+    , free >=4 && <=5
+    , mtl >=2 && <=2.2.1
+    , text >=1.2 && <=1.2.2.2
+    , transformers >=0.5.2 && <=0.5.5
   exposed-modules:
       Postlude
   other-modules:
diff --git a/src/Postlude.hs b/src/Postlude.hs
index 409b3dd..7701234 100644
--- a/src/Postlude.hs
+++ b/src/Postlude.hs
@@ -1,6 +1,4 @@
 {-# LANGUAGE NoImplicitPrelude #-}
-{-# LANGUAGE RankNTypes #-}
-{-# LANGUAGE TypeInType #-}
 
 -- The following maps all imports into a single module alias for easy exporting.
 -- In all cases, we choose to explicitly list all exports (and avoid the use of
@@ -10,10 +8,7 @@
 -- It is generally expected one will add the -XNoImplicitPrelude pragma to the
 -- file Postlude is being used in, and to import Postlude without any
 -- qualification.
-module Postlude
-( module X
-, undefined
-) where
+module Postlude (module X) where
 
 import Control.Applicative as X
   ( Applicative, (*>), (<*), (<*>), pure
@@ -214,6 +209,7 @@ import GHC.Enum as X
 
 import GHC.Err as X
   ( error
+  , undefined
   )
 
 import GHC.Float as X
@@ -309,11 +305,3 @@ import System.IO as X
 import Text.Read as X
   ( read
   )
-
-import qualified GHC.Err as Err
-import qualified GHC.Stack.Types as Stack.Types
-import qualified GHC.Types as GHC.Types
-
-undefined :: forall (r :: GHC.Types.RuntimeRep). forall (a :: GHC.Types.TYPE r).
-             Stack.Types.HasCallStack => a
-undefined = Err.error "Postlude.undefined"