diff --git a/lib/math.c b/lib/math.c
index 5268663..58c09f4 100644
--- a/lib/math.c
+++ b/lib/math.c
@@ -13,7 +13,7 @@ long square(uint num) {
 	long sum = num - 1;
 	while(num > 0) {
 		sum += num*2;
-		sum--;
+		num--;
 	}
 	return sum + 1;
 }