--- a/include/netinet/in.h
+++ b/include/netinet/in.h
@@ -146,7 +146,7 @@ uint16_t ntohs(uint16_t);
         (IN6_IS_ADDR_MULTICAST(a) && ((((uint8_t *) (a))[1] & 0xf) == 0xe))
 
 #define __ARE_4_EQUAL(a,b) \
-	(!( 0[a]-0[b] | 1[a]-1[b] | 2[a]-2[b] | 3[a]-3[b] ))
+	(!( (0[a]-0[b]) | (1[a]-1[b]) | (2[a]-2[b]) | (3[a]-3[b]) ))
 #define IN6_ARE_ADDR_EQUAL(a,b) \
 	__ARE_4_EQUAL((const uint32_t *)(a), (const uint32_t *)(b))