diff --git a/nix/overlay.nix b/nix/overlay.nix
index 4545ef2..457688c 100644
--- a/nix/overlay.nix
+++ b/nix/overlay.nix
@@ -16,7 +16,6 @@ let
       hackage "first-class-families" "0.8.0.1" "0h1rxbc7zsxrlhx5xcl58wjx3qi2wny8wb3sk7c1qnydf4ckcckz";
     dump-core = hackage "dump-core" "0.1.3.2" "1mi8p736yn00z549pwnjv4ydwbs8mwg6dla3ly447c027nq8py6g";
     monadLib = hackage "monadLib" "3.10" "1v4ynjcb963s3lfw3v71qdzvld1mmz1faf8swhvicma5jbvwchy2";
-    type-errors-pretty = pkgs.haskell.lib.doJailbreak super.type-errors-pretty;
   };
 
   pkgs = import nixpkgs { inherit system; };
diff --git a/package.yaml b/package.yaml
index 748dd75..fed00ca 100644
--- a/package.yaml
+++ b/package.yaml
@@ -29,7 +29,6 @@ dependencies:
 - unagi-chan >= 0.4.0.0 && < 0.5
 - async >= 2.2 && < 3
 - type-errors >= 0.2.0.0
-- type-errors-pretty >= 0.0.0.0 && < 0.1
 - QuickCheck >= 2.11.3 && < 3
 
 custom-setup:
diff --git a/polysemy.cabal b/polysemy.cabal
index dd76aae..55370ca 100644
--- a/polysemy.cabal
+++ b/polysemy.cabal
@@ -120,7 +120,6 @@ library
     , th-abstraction >=0.3.1.0 && <0.5
     , transformers >=0.5.2.0 && <0.6
     , type-errors >=0.2.0.0
-    , type-errors-pretty >=0.0.0.0 && <0.1
     , unagi-chan >=0.4.0.0 && <0.5
   if impl(ghc < 8.6)
     default-extensions:
@@ -203,7 +202,6 @@ test-suite polysemy-test
     , th-abstraction >=0.3.1.0 && <0.5
     , transformers >=0.5.2.0 && <0.6
     , type-errors >=0.2.0.0
-    , type-errors-pretty >=0.0.0.0 && <0.1
     , unagi-chan >=0.4.0.0 && <0.5
   if impl(ghc < 8.6)
     default-extensions:
@@ -250,7 +248,6 @@ benchmark polysemy-bench
     , th-abstraction >=0.3.1.0 && <0.5
     , transformers >=0.5.2.0 && <0.6
     , type-errors >=0.2.0.0
-    , type-errors-pretty >=0.0.0.0 && <0.1
     , unagi-chan >=0.4.0.0 && <0.5
   if impl(ghc < 8.6)
     default-extensions:
diff --git a/src/Polysemy/Internal/CustomErrors.hs b/src/Polysemy/Internal/CustomErrors.hs
index 6117fe5..3621a0f 100644
--- a/src/Polysemy/Internal/CustomErrors.hs
+++ b/src/Polysemy/Internal/CustomErrors.hs
@@ -13,6 +13,8 @@ module Polysemy.Internal.CustomErrors
   , UnhandledEffect
   , DefiningModule
   , DefiningModuleForEffect
+  , type (<>)
+  , type (%)
   ) where
 
 import Data.Kind
@@ -21,7 +23,6 @@ import GHC.TypeLits (Symbol)
 import Polysemy.Internal.Kind
 import Polysemy.Internal.CustomErrors.Redefined
 import Type.Errors hiding (IfStuck, WhenStuck, UnlessStuck)
-import Type.Errors.Pretty (type (<>), type (%))
 
 
 ------------------------------------------------------------------------------
@@ -36,6 +37,20 @@ type family DefiningModuleForEffect (e :: k) :: Symbol where
   DefiningModuleForEffect (e a) = DefiningModuleForEffect e
   DefiningModuleForEffect e     = DefiningModule e
 
+-- These are taken from type-errors-pretty because it's not in stackage for 9.0.1
+-- See https://github.com/polysemy-research/polysemy/issues/401
+type family ToErrorMessage (t :: k) :: ErrorMessage where
+    ToErrorMessage (t :: Symbol) = 'Text t
+    ToErrorMessage (t :: ErrorMessage) = t
+    ToErrorMessage t = 'ShowType t
+
+infixl 5 <>
+type family (<>) (l :: k1) (r :: k2) :: ErrorMessage where
+    l <> r = ToErrorMessage l ':<>: ToErrorMessage r
+
+infixr 4 %
+type family (%) (t :: k1) (b :: k2) :: ErrorMessage where
+    t % b = ToErrorMessage t ':$$: ToErrorMessage b
 
 -- TODO(sandy): Put in type-errors
 type ShowTypeBracketed t = "(" <> t <> ")"
diff --git a/src/Polysemy/Internal/Index.hs b/src/Polysemy/Internal/Index.hs
index 9c307dc..f4ebe3c 100644
--- a/src/Polysemy/Internal/Index.hs
+++ b/src/Polysemy/Internal/Index.hs
@@ -9,8 +9,8 @@ module Polysemy.Internal.Index where
 
 import GHC.TypeLits (Nat)
 import Type.Errors (TypeError, ErrorMessage(ShowType))
-import Type.Errors.Pretty (type (<>), type (%))
 
+import Polysemy.Internal.CustomErrors (type (<>), type (%))
 import Polysemy.Internal.Sing (SList (SEnd, SCons))
 
 ------------------------------------------------------------------------------