diff -upr postgresql-13.1.orig/src/include/pg_config_manual.h postgresql-13.1/src/include/pg_config_manual.h
--- postgresql-13.1.orig/src/include/pg_config_manual.h	2020-11-10 00:24:30.000000000 +0200
+++ postgresql-13.1/src/include/pg_config_manual.h	2020-12-10 01:55:35.999605194 +0200
@@ -201,7 +201,7 @@
  * support them yet.
  */
 #ifndef WIN32
-#define DEFAULT_PGSOCKET_DIR  "/tmp"
+#define DEFAULT_PGSOCKET_DIR  "/run/postgresql"
 #else
 #define DEFAULT_PGSOCKET_DIR ""
 #endif