diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,10 @@
 
 [Current version](https://gitlab.com/lysxia/fcf-family/-/blob/main/fcf-family/CHANGELOG.md)
 
+## 0.2.0.2 - 2024-01-24
+
+- Compatibility up to GHC 9.12.1
+
 ## 0.2.0.1
 
 - Compatibility with GHC 9.8.1
diff --git a/fcf-family.cabal b/fcf-family.cabal
--- a/fcf-family.cabal
+++ b/fcf-family.cabal
@@ -1,6 +1,6 @@
 cabal-version:      3.0
 name:               fcf-family
-version:            0.2.0.1
+version:            0.2.0.2
 synopsis: Family of families: featherweight defunctionalization
 description:
   Promote regular type families to first-class,
@@ -30,7 +30,7 @@
       first-class-families,
       containers,
       template-haskell,
-      base >=4.15 && < 4.20
+      base >=4.15 && < 4.22
     hs-source-dirs:   src
     default-language: Haskell2010
 
diff --git a/src/Fcf/Family/Meta.hs b/src/Fcf/Family/Meta.hs
--- a/src/Fcf/Family/Meta.hs
+++ b/src/Fcf/Family/Meta.hs
@@ -1,4 +1,5 @@
 {-# LANGUAGE DataKinds, PolyKinds, TemplateHaskell, TypeFamilies #-}
+{-# OPTIONS_GHC -Wno-orphans #-}
 
 -- | 'Eval' and friends as part of the family of families.
 module Fcf.Family.Meta () where
diff --git a/test/Main.hs b/test/Main.hs
--- a/test/Main.hs
+++ b/test/Main.hs
@@ -1,9 +1,21 @@
-{-# LANGUAGE AllowAmbiguousTypes, DataKinds, PolyKinds, ScopedTypeVariables, TemplateHaskell, TypeApplications, TypeFamilies, TypeOperators #-}
+{-# LANGUAGE
+  AllowAmbiguousTypes,
+  CPP,
+  DataKinds,
+  PolyKinds,
+  ScopedTypeVariables,
+  TemplateHaskell,
+  TypeApplications,
+  TypeFamilies,
+  TypeOperators #-}
+{-# OPTIONS_GHC -Wno-orphans -fdefer-type-errors #-}
 -- {-# OPTIONS_GHC -ddump-splices #-}
 
 module Main where
 
+import Control.Exception (TypeError(..), try)
 import Data.Type.Bool
+import GHC.Stack (HasCallStack)
 import GHC.TypeNats
 
 import Fcf.Core
@@ -20,11 +32,13 @@
 fcfify ''Fst
 fcfify ''Snd
 
+#if __GLASGOW_HASKELL__ >= 910
+type (:+:) = MkName "ghc-internal" "GHC.Internal.TypeNats" "+"
+type If_ = MkName "ghc-internal" "GHC.Internal.Data.Type.Bool" "If"
+#else
 type (:+:) = MkName "base" "GHC.TypeNats" "+"
 type If_ = MkName "base" "Data.Type.Bool" "If"
-
-equals :: forall a b. (a ~ b) => IO ()
-equals = pure ()
+#endif
 
 main :: IO ()
 main = do
@@ -33,14 +47,15 @@
   equate @(Eval (Family If_ P1 '( 'False, '(1, '(2, '()))))) @2
 
   -- Test applyFamily
-  equals @(Eval $(applyFamily ''(+) [ [t|3|] , [t|4|] ])) @7
-  equals @(Eval $(applyFamily ''If [ [t|'True|] , [t|Int|] , [t|()|] ])) @Int
+  equate @(Eval $(applyFamily ''(+) [ [t|3|] , [t|4|] ])) @7
+  equate @(Eval $(applyFamily ''If [ [t|'True|] , [t|Int|] , [t|()|] ])) @Int
 
   -- Test kind inference: the two Any under If should have the same type.
   equate @(Eval (Family If_ P1 '( 'True, '(Any, '(Any, '()))))) @Any
 
   -- The following should fail because Family_ is untyped (unlike Family)
-  -- equate @(Eval (Family_ If_ P1 '( 'True, '(Any, '(Any, '()))))) @Any
+  -- -fdefer-type-errors only stops at lets.
+  shouldFail $ let err = equate @(Eval (Family_ If_ P1 '( 'True, '(Any, '(Any, '()))))) @Any in err
 
 -- Utils
 
@@ -48,3 +63,9 @@
 
 equate :: forall a b. (a ~ b) => IO ()
 equate = pure ()
+
+shouldFail :: HasCallStack => IO () -> IO ()
+shouldFail run = try run >>= \r ->
+  case r of
+    Left (TypeError _) -> pure ()
+    Right () -> error "This test should have failed, but didn't"