diff --git a/crypto/stack/stack.c b/crypto/stack/stack.c
index ea50175d1..c7173eb6a 100644
--- a/crypto/stack/stack.c
+++ b/crypto/stack/stack.c
@@ -334,7 +334,7 @@ void sk_sort(STACK *st)
 
 int sk_is_sorted(const STACK *st)
 	{
-	if (st)
+	if (!st)
 		return 1;
 	return st->sorted;
 	}