diff --git a/hsilop.hs b/hsilop.hs
index d241f0a..d346229 100644
--- a/hsilop.hs
+++ b/hsilop.hs
@@ -18,7 +18,7 @@ io f = interact (unlines . map f . filter (not . null) . lines)
 result :: Either String Double -> String
 result (Left err) = "Ꞥ∘ " ++ err
 result (Right x)  = printf ("ꟼ∘ " ++ format) x where
-  format = if ceiling n == floor n then "%.0f" else "%.10f"
+  format = if ceiling x == floor x then "%.0f" else "%.10f"
 
 
 -- Solve a RPN expression