diff --git a/ChangeLog.txt b/ChangeLog.txt
index 23cf4f508..3dc15e6b1 100644
--- a/ChangeLog.txt
+++ b/ChangeLog.txt
@@ -5,6 +5,7 @@ Broker:
 - Fix plugin cleanup function not being called on exit of the broker.
   Closes #900.
 - Print more OpenSSL errors when loading certificates/keys fail.
+- Use AF_UNSPEC etc. instead of PF_UNSPEC to comply with POSIX. Closes #863.
 
 
 1.5 - 20180502
diff --git a/lib/net_mosq.c b/lib/net_mosq.c
index daf8ce94b..11d7fad62 100644
--- a/lib/net_mosq.c
+++ b/lib/net_mosq.c
@@ -248,9 +248,9 @@ int net__try_connect_step2(struct mosquitto *mosq, uint16_t port, mosq_sock_t *s
 		*sock = socket(rp->ai_family, rp->ai_socktype, rp->ai_protocol);
 		if(*sock == INVALID_SOCKET) continue;
 
-		if(rp->ai_family == PF_INET){
+		if(rp->ai_family == AF_INET){
 			((struct sockaddr_in *)rp->ai_addr)->sin_port = htons(port);
-		}else if(rp->ai_family == PF_INET6){
+		}else if(rp->ai_family == AF_INET6){
 			((struct sockaddr_in6 *)rp->ai_addr)->sin6_port = htons(port);
 		}else{
 			COMPAT_CLOSE(*sock);
@@ -310,7 +310,7 @@ int net__try_connect(struct mosquitto *mosq, const char *host, uint16_t port, mo
 
 	*sock = INVALID_SOCKET;
 	memset(&hints, 0, sizeof(struct addrinfo));
-	hints.ai_family = PF_UNSPEC;
+	hints.ai_family = AF_UNSPEC;
 	hints.ai_flags = AI_ADDRCONFIG;
 	hints.ai_socktype = SOCK_STREAM;
 
@@ -333,9 +333,9 @@ int net__try_connect(struct mosquitto *mosq, const char *host, uint16_t port, mo
 		*sock = socket(rp->ai_family, rp->ai_socktype, rp->ai_protocol);
 		if(*sock == INVALID_SOCKET) continue;
 
-		if(rp->ai_family == PF_INET){
+		if(rp->ai_family == AF_INET){
 			((struct sockaddr_in *)rp->ai_addr)->sin_port = htons(port);
-		}else if(rp->ai_family == PF_INET6){
+		}else if(rp->ai_family == AF_INET6){
 			((struct sockaddr_in6 *)rp->ai_addr)->sin6_port = htons(port);
 		}else{
 			COMPAT_CLOSE(*sock);
diff --git a/src/conf.c b/src/conf.c
index f3d812dbc..9af80224d 100644
--- a/src/conf.c
+++ b/src/conf.c
@@ -114,7 +114,7 @@ static int conf__attempt_resolve(const char *host, const char *text, int log, co
 	int rc;
 
 	memset(&gai_hints, 0, sizeof(struct addrinfo));
-	gai_hints.ai_family = PF_UNSPEC;
+	gai_hints.ai_family = AF_UNSPEC;
 	gai_hints.ai_flags = AI_ADDRCONFIG;
 	gai_hints.ai_socktype = SOCK_STREAM;
 	gai_res = NULL;
diff --git a/src/net.c b/src/net.c
index 2326918be..6093dee92 100644
--- a/src/net.c
+++ b/src/net.c
@@ -353,7 +353,7 @@ int net__socket_listen(struct mosquitto__listener *listener)
 
 	snprintf(service, 10, "%d", listener->port);
 	memset(&hints, 0, sizeof(struct addrinfo));
-	hints.ai_family = PF_UNSPEC;
+	hints.ai_family = AF_UNSPEC;
 	hints.ai_flags = AI_PASSIVE;
 	hints.ai_socktype = SOCK_STREAM;