diff --git a/src/Data/Sequence/ToolsYj.hs b/src/Data/Sequence/ToolsYj.hs
new file mode 100644
--- /dev/null
+++ b/src/Data/Sequence/ToolsYj.hs
@@ -0,0 +1,11 @@
+{-# LANGUAGE ImportQualifiedPost #-}
+{-# OPTIONS_GHC -Wall -fno-warn-tabs #-}
+
+module Data.Sequence.ToolsYj (splitAt') where
+
+import Data.Sequence qualified as Seq
+
+splitAt' :: Int -> Seq.Seq a -> Maybe (Seq.Seq a, Seq.Seq a)
+splitAt' n s
+	| Seq.length s < n = Nothing
+	| otherwise = Just $ Seq.splitAt n s
diff --git a/tools-yj.cabal b/tools-yj.cabal
--- a/tools-yj.cabal
+++ b/tools-yj.cabal
@@ -5,7 +5,7 @@
 -- see: https://github.com/sol/hpack
 
 name:           tools-yj
-version:        0.1.0.32
+version:        0.1.0.33
 synopsis:       Tribial tools
 description:    Please see the README on GitHub at <https://github.com/YoshikuniJujo/tools-yj#readme>
 category:       Tools
@@ -39,6 +39,7 @@
       Data.List.ToolsYj
       Data.Maybe.ToolsYj
       Data.Ord.ToolsYj
+      Data.Sequence.ToolsYj
       Data.Sequences.ToolsYj
       Data.Text.ToolsYj
       Data.Tuple.ToolsYj