diff --git a/src/include/libpq/pqcomm.h b/src/include/libpq/pqcomm.h
index 6c8bc29ace..781d86c8ef 100644
--- a/src/include/libpq/pqcomm.h
+++ b/src/include/libpq/pqcomm.h
@@ -68,10 +68,10 @@ typedef struct
 /* Configure the UNIX socket location for the well known port. */
 
 #define UNIXSOCK_PATH(path, port, sockdir) \
+	   (AssertMacro(sockdir), \
+		AssertMacro(*(sockdir) != '\0'), \
 		snprintf(path, sizeof(path), "%s/.s.PGSQL.%d", \
-				((sockdir) && *(sockdir) != '\0') ? (sockdir) : \
-				DEFAULT_PGSOCKET_DIR, \
-				(port))
+				 (sockdir), (port)))
 
 /*
  * The maximum workable length of a socket path is what will fit into
diff --git a/src/include/pg_config_manual.h b/src/include/pg_config_manual.h
index 569af6997c..b4ce53300b 100644
--- a/src/include/pg_config_manual.h
+++ b/src/include/pg_config_manual.h
@@ -191,6 +191,11 @@
  * directory.  But if you just hate the idea of sockets in /tmp,
  * here's where to twiddle it.  You can also override this at runtime
  * with the postmaster's -k switch.
+ *
+ * If set to an empty string, then AF_UNIX sockets are not used by default: A
+ * server will not create an AF_UNIX socket unless the run-time configuration
+ * is changed, a client will connect via TCP/IP by default and will only use
+ * an AF_UNIX socket if one is explicitly specified.
  */
 #define DEFAULT_PGSOCKET_DIR  "/tmp"
 
diff --git a/src/interfaces/libpq/fe-connect.c b/src/interfaces/libpq/fe-connect.c
index 2e2d217352..99cd6c4117 100644
--- a/src/interfaces/libpq/fe-connect.c
+++ b/src/interfaces/libpq/fe-connect.c
@@ -1095,12 +1095,17 @@ connectOptions2(PGconn *conn)
 			if (ch->host)
 				free(ch->host);
 #ifdef HAVE_UNIX_SOCKETS
-			ch->host = strdup(DEFAULT_PGSOCKET_DIR);
-			ch->type = CHT_UNIX_SOCKET;
-#else
-			ch->host = strdup(DefaultHost);
-			ch->type = CHT_HOST_NAME;
+			if (DEFAULT_PGSOCKET_DIR[0])
+			{
+				ch->host = strdup(DEFAULT_PGSOCKET_DIR);
+				ch->type = CHT_UNIX_SOCKET;
+			}
+			else
 #endif
+			{
+				ch->host = strdup(DefaultHost);
+				ch->type = CHT_HOST_NAME;
+			}
 			if (ch->host == NULL)
 				goto oom_error;
 		}