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:	0.0.43
+version:	0.0.48
 stability:	alpha
 author:		Yoshikuni Jujo <PAF01143@nifty.ne.jp>
 maintainer:	Yoshikuni Jujo <PAF01143@nifty.ne.jp>
diff --git a/src/Graphics/UI/GLUT/Turtle/TriangleTools.hs b/src/Graphics/UI/GLUT/Turtle/TriangleTools.hs
--- a/src/Graphics/UI/GLUT/Turtle/TriangleTools.hs
+++ b/src/Graphics/UI/GLUT/Turtle/TriangleTools.hs
@@ -28,7 +28,8 @@
 dol (a : ps@(b : ps'@(c : _)))
 	| online (a, b, c) = a : dol ps'
 	| otherwise = a : dol ps
-dol p = error $ "dol: not implemented " ++ show p
+dol ps = ps
+-- dol p = error $ "dol: not implemented " ++ show p
 
 maximumIndex :: Ord a => [a] -> Int
 maximumIndex = fst . maximumIndexGen
@@ -87,7 +88,7 @@
 isRight :: (Pos, Pos, Pos) -> Bool
 isRight ((xa, ya), (xb, yb), (xc, yc))
 	| 0 < xd * ye - xe * yd = True
-	| 0 == xd * ye - xe * yd = error "bad triangle"
+	| 0 == xd * ye - xe * yd = error "isRight: bad triangle"
 	| otherwise = False
 	where
 	(xd, yd) = (xa - xb, ya - yb)
diff --git a/src/Graphics/UI/GLUT/Turtle/Triangles.hs b/src/Graphics/UI/GLUT/Turtle/Triangles.hs
--- a/src/Graphics/UI/GLUT/Turtle/Triangles.hs
+++ b/src/Graphics/UI/GLUT/Turtle/Triangles.hs
@@ -3,19 +3,22 @@
 import Graphics.UI.GLUT.Turtle.TriangleTools
 
 isHoleRight :: [Pos] -> Bool
+isHoleRight ps
+	| length (deleteOnline $ deletePoint ps) < 3 = True
 isHoleRight ps = isRight tri
 	where
-	i = far ps
-	tri = index3 ps i
+	i = far (deleteOnline $ deletePoint ps)
+	tri = index3 (deleteOnline $ deletePoint ps) i
 
 toTriangles :: [Pos] -> [(Pos, Pos, Pos)]
 toTriangles ps
+	| length ps < 3 = []
 	| isHoleRight ps = toTriangles' ps
 	| otherwise = toTriangles' $ reverse ps
 
 toTriangles' :: [Pos] -> [(Pos, Pos, Pos)]
 toTriangles' ps
-	| length ps < 3 = []
+	| length (deleteOnline $ deletePoint ps) < 3 = []
 	| otherwise = toTrianglesTop $ deleteOnline $ deletePoint ps
 
 deletePoint :: Eq a => [a] -> [a]
diff --git a/tests/testGLUT.hs b/tests/testGLUT.hs
--- a/tests/testGLUT.hs
+++ b/tests/testGLUT.hs
@@ -44,7 +44,7 @@
 processInput _ _ t "hide" = hideturtle t >> return True
 processInput _ _ t "bred" = bgcolor t ((255, 0, 0) :: (Int, Int, Int)) >> return True
 processInput _ _ t "bgreen" = bgcolor t ((0, 255, 0) :: (Int, Int, Int)) >> return True
-processInput _ _ t "home" = goto t 0 0 >> return True
+-- processInput _ _ t "home" = goto t 0 0 >> return True
 processInput _ _ t "undo" = undo t >> return True
 processInput f _ _ "size" = setFieldSize f 100 200 >> return True
 processInput f _ _ "topleft" = topleft f >> return True
@@ -52,4 +52,5 @@
 processInput _ _ t "goto100" = goto t 100 100 >> return True
 processInput _ _ t "clear" = clear t >> return True
 processInput _ _ t "svg" = getSVG t >>= print >> return True
+processInput _ _ t "home" = home t >> return True
 processInput _ _ _ _ = return True