diff --git a/dns/dns_name4_domain.3 b/dns/dns_name4_domain.3
index 88b0909..dabc5c5 100644
--- a/dns/dns_name4_domain.3
+++ b/dns/dns_name4_domain.3
@@ -4,11 +4,15 @@ dns_name4_domain \- construct host name for reverse lookup
 .SH SYNTAX
 .B #include <dns.h>
 
-int \fBdns_name4_domain\fP(char \fIq\fR[DNS_NAME4_DOMAIN],
+void \fBdns_name4_domain\fP(char \fIq\fR[DNS_NAME4_DOMAIN],
                      const char* \fIip\fR[4]);
 .SH DESCRIPTION
 dns_name4_domain is a low-level component of dns_name4.  It converts an
 IP address such as 1.2.3.4 into a domain name such as
 4.3.2.1.in-addr.arpa and places the packet-encoded domain name into \fIq\fR.
+
+q is zero terminated.
+
+q must have space for DNS_NAME4_DOMAIN bytes.
 .SH "SEE ALSO"
 dns_name4(3), dns_name6_domain(3)
diff --git a/dns/dns_name6_domain.3 b/dns/dns_name6_domain.3
index 455b867..458f44e 100644
--- a/dns/dns_name6_domain.3
+++ b/dns/dns_name6_domain.3
@@ -4,7 +4,7 @@ dns_name6_domain \- construct host name for reverse lookup
 .SH SYNTAX
 .B #include <dns.h>
 
-int \fBdns_name6_domain\fP(char \fIq\fR[DNS_NAME6_DOMAIN],
+void \fBdns_name6_domain\fP(char \fIq\fR[DNS_NAME6_DOMAIN],
                      const char* \fIip\fR[16],int \fItype\fR);
 .SH DESCRIPTION
 dns_name6_domain is a low-level component of dns_name6.  It converts an
@@ -15,5 +15,9 @@ and places the packet-encoded domain name into \fIq\fR.
 \fItype\fR can be DNS_IP6_INT or DNS_IP6_ARPA.  The "ip6.int" domain for
 IPv6 reverse lookups is now deprecated and "ip6.arpa" is the standard
 way.
+
+q is zero terminated.
+
+q must have space for DNS_NAME4_DOMAIN bytes.
 .SH "SEE ALSO"
 dns_name6(3), dns_name4_domain(3)
diff --git a/dns/dns_nd6.c b/dns/dns_nd6.c
index 0376a22..222f9ea 100644
--- a/dns/dns_nd6.c
+++ b/dns/dns_nd6.c
@@ -14,7 +14,7 @@ static char tohex(char c) {
   return c>=10?c-10+'a':c+'0';
 }
 
-int dns_name6_domain(char name[DNS_NAME6_DOMAIN],const char ip[16],int t)
+void dns_name6_domain(char name[DNS_NAME6_DOMAIN],const char ip[16],int t)
 {
   unsigned int j;
 
@@ -28,7 +28,5 @@ int dns_name6_domain(char name[DNS_NAME6_DOMAIN],const char ip[16],int t)
     byte_copy(name + 4*16,9,"\3ip6\3int\0");
   else if (t==DNS_IP6_ARPA)
     byte_copy(name + 4*16,10,"\3ip6\4arpa\0");
-  else return 0;
-  return 4*16+9+t;
 }