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-rw-r--r--src/Xanthous/Data.hs3
1 files changed, 2 insertions, 1 deletions
diff --git a/src/Xanthous/Data.hs b/src/Xanthous/Data.hs
index ff11a8da7f80..b7df191e58a8 100644
--- a/src/Xanthous/Data.hs
+++ b/src/Xanthous/Data.hs
@@ -136,7 +136,8 @@ diffPositions (Position x₁ y₁) (Position x₂ y₂) = Position (x₁ - x₂)
 --
 -- ∀ dir :: Direction. isUnit ('asPosition' dir)
 isUnit :: Position -> Bool
-isUnit (Position px py) = abs px == 1 || abs py == 1
+isUnit (Position px py) =
+  abs px `elem` [0,1] && abs py `elem` [0, 1] && (px, py) /= (0, 0)
 
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