1 files changed, 1 insertions, 1 deletions
diff --git a/lib/ipv4.h b/lib/ipv4.h
index 49aa13a6..4c4fab90 100644
--- a/lib/ipv4.h
+++ b/lib/ipv4.h
@@ -53,7 +53,7 @@ typedef u32 ip_addr;
 #define ipa_hton(x) x = _MI(htonl(_I(x)))
 #define ipa_ntoh(x) x = _MI(ntohl(_I(x)))
 #define ipa_classify(x) ipv4_classify(_I(x))
-#define ipa_opposite(x) _MI(_I(x) ^ 1)
+#define ipa_opposite(x,len) _MI(_I(x) ^ (len == 30 ? 3 : 1))
 #define ipa_class_mask(x) _MI(ipv4_class_mask(_I(x)))
 #define ipa_from_u32(x) _MI(x)
 #define ipa_to_u32(x) _I(x)