1 files changed, 1 insertions, 1 deletions
diff --git a/pascal.icl b/pascal.icl
index f1aafbc..d916aa8 100644
--- a/pascal.icl
+++ b/pascal.icl
@@ -57,7 +57,7 @@ repeatn n x	= take n (repeat x)
 spaces :: !.Int -> [Char]
 spaces n = repeatn n ' '
 
-class toString a :: a -> String
+class toString a :: !a -> String
 
 instance toString [Char] where toString a = {c \\ c <- a}
 instance toString Int where toString a = code inline {