diff --git a/src/3n+1/Main.hs b/src/3n+1/Main.hs
index ec9d22e..1ef460a 100644
--- a/src/3n+1/Main.hs
+++ b/src/3n+1/Main.hs
@@ -30,14 +30,15 @@ f :: Integer -> Integer
 f n = s 1 n
   where
     s :: Integer -> Integer -> Integer
-    s i n
-      | n ==    1  = i
-      | n ==    0  = i
-      | n ==  (-1) = i
-      | n ==  (-5) = i
-      | n == (-17) = i
-      | even n = s (succ i) (n `div` 2)
-      | odd  n = s (succ i) (3*n + 1)
+    s c n
+      | n ==    1  = c
+      | n ==    0  = c
+      | n ==  (-1) = c
+      | n ==  (-5) = c
+      | n == (-17) = c
+      | even n = s c' (n `div` 2)
+      | odd  n = s c' (3*n + 1)
+      where c' = succ c
 
 f' :: Integer -> Integer
 f' n = f'' 1 n