1 files changed, 1 insertions, 1 deletions
diff --git a/lib/ipv4.h b/lib/ipv4.h
index 5cb2835..033116b 100644
--- a/lib/ipv4.h
+++ b/lib/ipv4.h
@@ -53,7 +53,7 @@ typedef u32 ip_addr;
 #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_class_mask(x) x = _MI(ipv4_class_mask(_I(x)))
+#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)
 #define ipa_compare(x,y) ipv4_compare(_I(x),_I(y))