diff --git a/src/other.c b/src/other.c
index 5467fb1..aea5aa8 100644
--- a/src/other.c
+++ b/src/other.c
@@ -354,11 +354,11 @@ double get_range_size_v6(const struct range_t *r)
  */
 int xstrstr_init(struct conf_t *state, const char *restrict str)
 {
-	if (memcmp("lease ", str, 6)) {
+	if (!memcmp("lease ", str, 6)) {
 		set_ipv_functions(state, IPv4);
 		return PREFIX_LEASE;
 	}
-	if (memcmp("  iaaddr ", str, 9)) {
+	if (!memcmp("  iaaddr ", str, 9)) {
 		set_ipv_functions(state, IPv6);
 		return PREFIX_LEASE;
 	}