diff --git a/ChangeLog.md b/ChangeLog.md
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -1,5 +1,11 @@
 # Changelog for homotuple
 
+## 0.2.1.0
+
+2023.08.17
+
+Support [OneTuple](https://hackage.haskell.org/package/OneTuple) 0.3, 0.4.
+
 ## 0.2.0.0
 
 2021.03.19
diff --git a/homotuple.cabal b/homotuple.cabal
--- a/homotuple.cabal
+++ b/homotuple.cabal
@@ -1,7 +1,7 @@
-cabal-version: 1.12
+cabal-version: 2.2
 
 name:           homotuple
-version:        0.2.0.0
+version:        0.2.1.0
 synopsis:       Homotuple, all whose elements are the same type
 description:    Homotuple, all whose elements are the same type
 category:       Data
@@ -14,9 +14,11 @@
 license-file:   LICENSE
 build-type:     Custom
 
-extra-source-files:
+extra-doc-files:
     README.md
     ChangeLog.md
+
+extra-source-files:
     template/Homotuple.hs
     template/HomotupleItem.hs
 
@@ -26,9 +28,9 @@
 
 custom-setup
   setup-depends:
-      Cabal
-    , base
-    , directory
+      Cabal >=2 && <4,
+      base >=4.10 && <5,
+      directory >=1.3 && <1.4
 
 library
   exposed-modules:      Data.Tuple.Homotuple
@@ -48,8 +50,8 @@
                         -Widentities
                         -Wredundant-constraints
                         -Wno-name-shadowing
-  build-depends:        base >=4.10 && <4.15,
-                        OneTuple >=0.2 && <0.3,
+  build-depends:        base >=4.10 && <5,
+                        OneTuple >=0.2 && <0.5,
                         Only >=0.1 && <0.2,
                         single-tuple >=0.1 && <0.2
   if impl(ghc >= 8.4.0)
diff --git a/src/Data/Tuple/Homotuple/OneTuple.hs b/src/Data/Tuple/Homotuple/OneTuple.hs
--- a/src/Data/Tuple/Homotuple/OneTuple.hs
+++ b/src/Data/Tuple/Homotuple/OneTuple.hs
@@ -1,7 +1,13 @@
+{-# LANGUAGE CPP          #-}
 {-# LANGUAGE DataKinds    #-}
-{-# LANGUAGE Trustworthy  #-}
 {-# LANGUAGE TypeFamilies #-}
 
+#if MIN_VERSION_OneTuple(0,3,0) && MIN_VERSION_base(4,15,0)
+{-# LANGUAGE Safe #-}
+#else
+{-# LANGUAGE Trustworthy #-}
+#endif
+
 {-# OPTIONS_GHC -Wno-orphans #-}
 
 {-# OPTIONS_HADDOCK show-extensions #-}
@@ -17,7 +23,22 @@
 
 module Data.Tuple.Homotuple.OneTuple () where
 
+#if MIN_VERSION_OneTuple(0,3,0)
+#if !MIN_VERSION_base(4,15,0)
 import Data.Tuple.Homotuple (Homotuple, errorLengthMismatch)
+import Data.Tuple.Solo      (Solo (Solo))
+import GHC.Exts             (IsList (Item, fromList, toList))
+
+type instance Homotuple 1 a = Solo a
+
+instance IsList (Solo a) where
+  type Item (Solo a) = a
+  fromList [a] = Solo a
+  fromList _   = errorLengthMismatch
+  toList (Solo a) = [a]
+#endif
+#else
+import Data.Tuple.Homotuple (Homotuple, errorLengthMismatch)
 import Data.Tuple.OneTuple  (OneTuple (OneTuple))
 import GHC.Exts             (IsList (Item, fromList, toList))
 
@@ -28,3 +49,4 @@
   fromList [a] = OneTuple a
   fromList _   = errorLengthMismatch
   toList (OneTuple a) = [a]
+#endif
diff --git a/template/Homotuple.hs b/template/Homotuple.hs
--- a/template/Homotuple.hs
+++ b/template/Homotuple.hs
@@ -52,7 +52,7 @@
 import           Data.Tuple.Single   (Single (wrap))
 import           GHC.Exts            (IsList (Item, fromList, toList))
 import           GHC.Stack           (HasCallStack)
-import           GHC.TypeLits        (type (*), type (+), KnownNat, Nat, natVal)
+import           GHC.TypeLits        (KnownNat, Nat, natVal, type (*), type (+))
 
 type family Homotuple (n :: Nat) (a :: Type) = (t :: Type) | t -> n