diff --git a/net/netfilter/nf_conntrack_sip.c b/net/netfilter/nf_conntrack_sip.c
index 046f118dea06..d16aa43ebd4d 100644
--- a/net/netfilter/nf_conntrack_sip.c
+++ b/net/netfilter/nf_conntrack_sip.c
@@ -605,7 +605,7 @@ int ct_sip_parse_numerical_param(const struct nf_conn *ct, const char *dptr,
 	start += strlen(name);
 	*val = simple_strtoul(start, &end, 0);
 	if (start == end)
-		return 0;
+		return -1;
 	if (matchoff && matchlen) {
 		*matchoff = start - dptr;
 		*matchlen = end - start;