diff --git a/gluturtle.cabal b/gluturtle.cabal
--- a/gluturtle.cabal
+++ b/gluturtle.cabal
@@ -2,7 +2,7 @@
 cabal-version:	>= 1.6
 
 name:		gluturtle
-version:	0.0.38
+version:	0.0.39
 stability:	alpha
 author:		Yoshikuni Jujo <PAF01143@nifty.ne.jp>
 maintainer:	Yoshikuni Jujo <PAF01143@nifty.ne.jp>
diff --git a/src/Graphics/UI/GLUT/Turtle/Move.hs b/src/Graphics/UI/GLUT/Turtle/Move.hs
--- a/src/Graphics/UI/GLUT/Turtle/Move.hs
+++ b/src/Graphics/UI/GLUT/Turtle/Move.hs
@@ -120,7 +120,7 @@
 drawTurtle :: Field -> TurtleState -> Double -> Position ->
 	Maybe Position -> IO ()
 drawTurtle f ts@TurtleState{fillcolor = fclr, pencolor = clr} dir pos
-	| [] <- makeShape ts dir pos = error $ show ts
+	| [] <- makeShape ts dir pos = const $ return () -- error $ show ts
 	| otherwise = maybe
 		(drawCharacter f fclr clr (makeShape ts dir pos) (pensize ts))
 		(drawCharacterAndLine f fclr clr (makeShape ts dir pos) (pensize ts) pos)