diff --git a/ChangeLog.md b/ChangeLog.md
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -6,6 +6,11 @@
 
 ### Other Changes
 
+## 1.7.1.0 (2021-11-23)
+
+### Other Changes
+
+* Support GHC 9.2.1
 
 ## 1.7.0.0 (2021-11-16)
 
diff --git a/polysemy.cabal b/polysemy.cabal
--- a/polysemy.cabal
+++ b/polysemy.cabal
@@ -5,7 +5,7 @@
 -- see: https://github.com/sol/hpack
 
 name:           polysemy
-version:        1.7.0.0
+version:        1.7.1.0
 synopsis:       Higher-order, low-boilerplate free monads.
 description:    Please see the README on GitHub at <https://github.com/polysemy-research/polysemy#readme>
 category:       Language
diff --git a/src/Polysemy/Internal/CustomErrors.hs b/src/Polysemy/Internal/CustomErrors.hs
--- a/src/Polysemy/Internal/CustomErrors.hs
+++ b/src/Polysemy/Internal/CustomErrors.hs
@@ -36,31 +36,6 @@
 type family (%) (t :: k1) (b :: k2) :: ErrorMessage where
     t % b = ToErrorMessage t ':$$: ToErrorMessage b
 
--- TODO(sandy): Put in type-errors
-type ShowTypeBracketed t = "(" <> t <> ")"
-
-
-------------------------------------------------------------------------------
--- | The constructor of the effect row --- it's either completely polymorphic,
--- a nil, or a cons.
-data EffectRowCtor = TyVarR | NilR | ConsR
-
-
-------------------------------------------------------------------------------
--- | Given that @r@ isn't stuck, determine which constructor it has.
-type family UnstuckRState (r :: EffectRow) :: EffectRowCtor where
-  UnstuckRState '[]      = 'NilR
-  UnstuckRState (_ ': _) = 'ConsR
-
-
-------------------------------------------------------------------------------
--- | Put brackets around @r@ if it's a cons.
-type family ShowRQuoted (rstate :: EffectRowCtor) (r :: EffectRow) :: ErrorMessage where
-  ShowRQuoted 'TyVarR r = 'ShowType r
-  ShowRQuoted 'NilR   r = 'ShowType r
-  ShowRQuoted 'ConsR  r = ShowTypeBracketed r
-
-
 data FirstOrderErrorFcf :: k -> Symbol -> Exp Constraint
 type instance Eval (FirstOrderErrorFcf e fn) = $(te[t|
     UnlessPhantom
diff --git a/src/Polysemy/Internal/Index.hs b/src/Polysemy/Internal/Index.hs
--- a/src/Polysemy/Internal/Index.hs
+++ b/src/Polysemy/Internal/Index.hs
@@ -2,16 +2,17 @@
 {-# LANGUAGE UndecidableInstances #-}
 {-# LANGUAGE FlexibleInstances #-}
 {-# LANGUAGE MultiParamTypeClasses #-}
+{-# LANGUAGE CPP #-}
 
 {-# OPTIONS_HADDOCK not-home #-}
 
 module Polysemy.Internal.Index where
 
 import GHC.TypeLits (Nat)
-import Type.Errors (TypeError, ErrorMessage(ShowType))
+import Type.Errors (ErrorMessage (ShowType), TypeError)
 
-import Polysemy.Internal.CustomErrors (type (<>), type (%))
-import Polysemy.Internal.Sing (SList (SEnd, SCons))
+import Polysemy.Internal.CustomErrors (type (%), type (<>))
+import Polysemy.Internal.Sing (SList (SCons, SEnd))
 
 ------------------------------------------------------------------------------
 -- | Infer a partition of the result type @full@ so that for the fixed segments
@@ -31,9 +32,16 @@
     insertAtIndex = SCons (insertAtIndex @_ @index @head @tail @oldTail @full)
     {-# INLINE insertAtIndex #-}
 
+-- Broken on 9.2.
+-- It appears that instance matching is done with an abstract value for @oldTail@, thus not matching the correct
+-- instance and finding only this one, causing a false positive for the @TypeError@.
+#if __GLASGOW_HASKELL__ < 902
+
 instance {-# INCOHERENT #-} TypeError (InsertAtFailure index oldTail head full)
        => InsertAtIndex index head tail oldTail full inserted where
   insertAtIndex = error "unreachable"
+
+#endif
 
 type family InsertAtUnprovidedIndex where
   InsertAtUnprovidedIndex = TypeError (