diff --git a/libc/netdb/getnameinfo.c b/libc/netdb/getnameinfo.c
index bd993a77..a84342d8 100644
--- a/libc/netdb/getnameinfo.c
+++ b/libc/netdb/getnameinfo.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2013 Jonas 'Sortie' Termansen.
+ * Copyright (c) 2013, 2016 Jonas 'Sortie' Termansen.
  *
  * Permission to use, copy, modify, and distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
@@ -17,10 +17,16 @@
  * Address-to-name translation in protocol-independent manner.
  */
 
-#include <netdb.h>
+#include <sys/socket.h>
 
+#include <arpa/inet.h>
+#include <endian.h>
+#include <errno.h>
+#include <netdb.h>
+#include <netinet/in.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 
 int getnameinfo(const struct sockaddr* restrict sa,
                 socklen_t salen,
@@ -30,13 +36,45 @@ int getnameinfo(const struct sockaddr* restrict sa,
                 socklen_t servlen,
                 int flags)
 {
-	(void) sa;
-	(void) salen;
-	(void) host;
-	(void) hostlen;
-	(void) serv;
-	(void) servlen;
-	(void) flags;
-	fprintf(stderr, "%s is not implemented, aborting.\n", __func__);
-	abort();
+	if ( flags & ~(NI_NOFQDN | NI_NUMERICHOST | NI_NAMEREQD | NI_NUMERICSERV |
+	               NI_NUMERICSCOPE | NI_DGRAM) )
+		return EAI_BADFLAGS;
+	int af;
+	if ( salen == sizeof(struct sockaddr_in) &&
+	     ((struct sockaddr_in*) sa)->sin_family == AF_INET )
+		af = AF_INET;
+	else if ( salen == sizeof(struct sockaddr_in6) &&
+	          ((struct sockaddr_in6*) sa)->sin6_family == AF_INET6 )
+		af = AF_INET6;
+	else
+		return EAI_FAMILY;
+	if ( !host && !serv )
+		return EAI_NONAME;
+	if ( host )
+	{
+		if ( flags & NI_NAMEREQD )
+			return EAI_NONAME;
+		const void* addr;
+		if ( af == AF_INET )
+			addr = &(((struct sockaddr_in*) sa)->sin_addr);
+		else if ( af == AF_INET6 )
+			addr = &(((struct sockaddr_in6*) sa)->sin6_addr);
+		else
+			return EAI_FAMILY;
+		if ( !inet_ntop(af, addr, host, hostlen) )
+			return errno == ENOSPC ? EAI_OVERFLOW :  EAI_NONAME;
+	}
+	if ( serv )
+	{
+		in_port_t port;
+		if ( af == AF_INET )
+			port = be16toh(((struct sockaddr_in*) sa)->sin_port);
+		else if ( af == AF_INET6 )
+			port = be16toh(((struct sockaddr_in6*) sa)->sin6_port);
+		else
+			return EAI_FAMILY;
+		if ( servlen <= (size_t) snprintf(serv, servlen, "%u", port) )
+			return EAI_OVERFLOW;
+	}
+	return 0;
 }