+diff -urpa postgresql-10.5.orig/src/bin/pg_upgrade/option.c postgresql-10.5/src/bin/pg_upgrade/option.c
+--- postgresql-10.5.orig/src/bin/pg_upgrade/option.c 2018-08-22 19:57:55.237373015 +0000
++++ postgresql-10.5/src/bin/pg_upgrade/option.c 2018-08-22 19:59:10.944372163 +0000
+@@ -460,6 +460,11 @@ get_sock_dir(ClusterInfo *cluster, bool
+ cluster->sockdir = pg_malloc(MAXPGPATH);
+ if (!getcwd(cluster->sockdir, MAXPGPATH))
+ pg_fatal("could not determine current directory\n");
++#ifndef UNIX_PATH_MAX
++#define UNIX_PATH_MAX 108
++#endif
++ if (strlen(cluster->sockdir) >= UNIX_PATH_MAX - sizeof(".s.PGSQL.50432"))
++ strcpy(cluster->sockdir, "/tmp"); /* fall back to tmp */
+ }
+ else
+ {
+diff -urpa postgresql-10.5.orig/src/include/pg_config_manual.h postgresql-10.5/src/include/pg_config_manual.h
+--- postgresql-10.5.orig/src/include/pg_config_manual.h 2018-08-22 19:57:55.095373017 +0000
++++ postgresql-10.5/src/include/pg_config_manual.h 2018-08-22 19:58:30.664372616 +0000
+@@ -181,7 +181,7 @@
+ * here's where to twiddle it. You can also override this at runtime
+ * with the postmaster's -k switch.
+ */
+-#define DEFAULT_PGSOCKET_DIR "/tmp"
++#define DEFAULT_PGSOCKET_DIR "/var/run/postgresql"
+
+ /*
+ * This is the default event source for Windows event log.