diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,6 @@
+## 0.3.0 (2024-06-01)
+* update singleraeh
+
 ## 0.2.1 (2024-05-25)
 * add `Demotable Doc` instance
 * single `ShowChar`
diff --git a/src/TypeLevelShow/Doc.hs b/src/TypeLevelShow/Doc.hs
--- a/src/TypeLevelShow/Doc.hs
+++ b/src/TypeLevelShow/Doc.hs
@@ -22,6 +22,7 @@
 import GHC.TypeLits qualified as TE -- TE = TypeError
 import GHC.TypeLits hiding ( ErrorMessage(..) )
 import Singleraeh.Demote
+import Singleraeh.SingI
 
 -- | Simple pretty document ADT.
 --
@@ -76,6 +77,17 @@
     (:$<>:) :: SDoc docl -> SDoc docr -> SDoc (docl :<>: docr)
     (:$$$:) :: SDoc docl -> SDoc docr -> SDoc (docl :$$: docr)
 
+-- | Demote an 'SDoc' singleton to the corresponding base 'Doc'.
+demoteDoc :: SDoc doc -> Doc String
+demoteDoc = \case
+  SText s   -> Text $ fromSSymbol s
+  l :$<>: r -> demoteDoc l :<>: demoteDoc r
+  l :$$$: r -> demoteDoc l :$$: demoteDoc r
+
+instance Demotable SDoc where
+    type Demote SDoc = Doc String
+    demote = demoteDoc
+
 -- | Produce the singleton for the given promoted 'Doc'.
 class SingDoc (doc :: PDoc) where
     singDoc :: SDoc doc
@@ -89,16 +101,9 @@
 instance (SingDoc l, SingDoc r) => SingDoc (l :$$: r) where
     singDoc = singDoc @l :$$$: singDoc @r
 
--- | Demote an 'SDoc' singleton to the corresponding base 'Doc'.
-demoteDoc :: SDoc doc -> Doc String
-demoteDoc = \case
-  SText s   -> Text $ fromSSymbol s
-  l :$<>: r -> demoteDoc l :<>: demoteDoc r
-  l :$$$: r -> demoteDoc l :$$: demoteDoc r
-
-instance Demotable SDoc where
-    type Demote SDoc = Doc String
-    demote = demoteDoc
+instance SingDoc doc => SingI doc where
+    type Sing = SDoc
+    sing' = singDoc
 
 -- | Reify a promoted 'Doc' to the corresponding term-level one.
 reifyDoc :: forall (doc :: PDoc). SingDoc doc => Doc String
diff --git a/type-level-show.cabal b/type-level-show.cabal
--- a/type-level-show.cabal
+++ b/type-level-show.cabal
@@ -5,7 +5,7 @@
 -- see: https://github.com/sol/hpack
 
 name:           type-level-show
-version:        0.2.1
+version:        0.3.0
 synopsis:       Utilities for writing Show-like type families
 description:    Please see README.md.
 category:       Types, Data
@@ -50,7 +50,7 @@
       MagicHash
   ghc-options: -Wall -Wno-unticked-promoted-constructors
   build-depends:
-      base >=4.16 && <5
+      base >=4.18 && <5
     , defun-core ==0.1.*
-    , singleraeh ==0.2.*
+    , singleraeh >=0.4.0 && <0.5
   default-language: GHC2021