diff --git a/lib/libc/db/hash/hash_page.c b/lib/libc/db/hash/hash_page.c
index 8040419f728e..a2bb7cfc84d2 100644
--- a/lib/libc/db/hash/hash_page.c
+++ b/lib/libc/db/hash/hash_page.c
@@ -677,7 +677,7 @@ overflow_page(HTAB *hashp)
 			bit = hashp->LAST_FREED &
 			    ((hashp->BSIZE << BYTE_SHIFT) - 1);
 			j = bit / BITS_PER_MAP;
-			bit = bit & ~(BITS_PER_MAP - 1);
+			bit = rounddown2(bit, BITS_PER_MAP);
 		} else {
 			bit = 0;
 			j = 0;
diff --git a/lib/libc/net/ip6opt.c b/lib/libc/net/ip6opt.c
index fda2cd4b8098..c2d292f2d966 100644
--- a/lib/libc/net/ip6opt.c
+++ b/lib/libc/net/ip6opt.c
@@ -130,8 +130,7 @@ inet6_option_append(struct cmsghdr *cmsg, const u_int8_t *typep, int multx,
 
 	/* calculate pad length before the option. */
 	off = bp - (u_char *)eh;
-	padlen = (((off % multx) + (multx - 1)) & ~(multx - 1)) -
-		(off % multx);
+	padlen = roundup2(off % multx, multx) - (off % multx);
 	padlen += plusy;
 	padlen %= multx;	/* keep the pad as short as possible */
 	/* insert padding */
@@ -200,7 +199,7 @@ inet6_option_alloc(struct cmsghdr *cmsg, int datalen, int multx, int plusy)
 
 	/* calculate pad length before the option. */
 	off = bp - (u_char *)eh;
-	padlen = (((off % multx) + (multx - 1)) & ~(multx - 1)) -
+	padlen = roundup2(off % multx, multx) -
 		(off % multx);
 	padlen += plusy;
 	padlen %= multx;	/* keep the pad as short as possible */
diff --git a/lib/libc/net/name6.c b/lib/libc/net/name6.c
index 1d37329a4d34..0023ecacdfbf 100644
--- a/lib/libc/net/name6.c
+++ b/lib/libc/net/name6.c
@@ -330,7 +330,7 @@ getipnodebyaddr(const void *src, size_t len, int af, int *errp)
 			*errp = NO_RECOVERY;
 			return NULL;
 		}
-		if ((long)src & ~(sizeof(struct in_addr) - 1)) {
+		if (rounddown2((long)src, sizeof(struct in_addr))) {
 			memcpy(&addrbuf, src, len);
 			src = &addrbuf;
 		}
@@ -343,7 +343,8 @@ getipnodebyaddr(const void *src, size_t len, int af, int *errp)
 			*errp = NO_RECOVERY;
 			return NULL;
 		}
-		if ((long)src & ~(sizeof(struct in6_addr) / 2 - 1)) {	/*XXX*/
+		if (rounddown2((long)src, sizeof(struct in6_addr) / 2)) {
+			/* XXX */
 			memcpy(&addrbuf, src, len);
 			src = &addrbuf;
 		}