diff --git a/nixos/doc/manual/release-notes/rl-1909.xml b/nixos/doc/manual/release-notes/rl-1909.xml
index b8cb83113266..97a381020139 100644
--- a/nixos/doc/manual/release-notes/rl-1909.xml
+++ b/nixos/doc/manual/release-notes/rl-1909.xml
@@ -62,6 +62,16 @@
      compatible with Python 3.
     </para>
    </listitem>
+   <listitem>
+    <para>
+     PostgreSQL now uses
+     <filename class="directory">/run/postgresql</filename> as its socket
+     directory instead of <filename class="directory">/tmp</filename>. So
+     if you run an application like eg. Nextcloud, where you need to use
+     the Unix socket path as the database host name, you need to change it
+     accordingly.
+    </para>
+   </listitem>
   </itemizedlist>
  </section>
 
diff --git a/nixos/modules/services/databases/postgresql.nix b/nixos/modules/services/databases/postgresql.nix
index aeab445a9983..87b236dd5fd1 100644
--- a/nixos/modules/services/databases/postgresql.nix
+++ b/nixos/modules/services/databases/postgresql.nix
@@ -238,6 +238,7 @@ in
             User = "postgres";
             Group = "postgres";
             PermissionsStartOnly = true;
+            RuntimeDirectory = "postgresql";
             Type = if lib.versionAtLeast cfg.package.version "9.6"
                    then "notify"
                    else "simple";
diff --git a/nixos/modules/services/web-apps/nextcloud.nix b/nixos/modules/services/web-apps/nextcloud.nix
index 5ad241ace5c8..eedcccac723c 100644
--- a/nixos/modules/services/web-apps/nextcloud.nix
+++ b/nixos/modules/services/web-apps/nextcloud.nix
@@ -172,7 +172,7 @@ in {
           Database host.
 
           Note: for using Unix authentication with PostgreSQL, this should be
-          set to <literal>/tmp</literal>.
+          set to <literal>/run/postgresql</literal>.
         '';
       };
       dbport = mkOption {
diff --git a/nixos/modules/services/web-apps/nextcloud.xml b/nixos/modules/services/web-apps/nextcloud.xml
index 098625aa02f2..dfefa55c5d5e 100644
--- a/nixos/modules/services/web-apps/nextcloud.xml
+++ b/nixos/modules/services/web-apps/nextcloud.xml
@@ -33,7 +33,7 @@
     config = {
       <link linkend="opt-services.nextcloud.config.dbtype">dbtype</link> = "pgsql";
       <link linkend="opt-services.nextcloud.config.dbuser">dbuser</link> = "nextcloud";
-      <link linkend="opt-services.nextcloud.config.dbhost">dbhost</link> = "/tmp"; # nextcloud will add /.s.PGSQL.5432 by itself
+      <link linkend="opt-services.nextcloud.config.dbhost">dbhost</link> = "/run/postgresql"; # nextcloud will add /.s.PGSQL.5432 by itself
       <link linkend="opt-services.nextcloud.config.dbname">dbname</link> = "nextcloud";
       <link linkend="opt-services.nextcloud.config.adminpassFile">adminpassFile</link> = "/path/to/admin-pass-file";
       <link linkend="opt-services.nextcloud.config.adminuser">adminuser</link> = "root";
diff --git a/pkgs/servers/sql/postgresql/default.nix b/pkgs/servers/sql/postgresql/default.nix
index 44559885850f..b42a494ff106 100644
--- a/pkgs/servers/sql/postgresql/default.nix
+++ b/pkgs/servers/sql/postgresql/default.nix
@@ -60,7 +60,7 @@ let
         (if atLeast "9.6" then ./patches/less-is-more-96.patch             else ./patches/less-is-more.patch)
         (if atLeast "9.6" then ./patches/hardcode-pgxs-path-96.patch       else ./patches/hardcode-pgxs-path.patch)
         ./patches/specify_pkglibdir_at_runtime.patch
-      ];
+      ] ++ lib.optional stdenv.isLinux ./patches/socketdir-in-run.patch;
 
     installTargets = [ "install-world" ];
 
diff --git a/pkgs/servers/sql/postgresql/patches/socketdir-in-run.patch b/pkgs/servers/sql/postgresql/patches/socketdir-in-run.patch
new file mode 100644
index 000000000000..969f80ff8fc7
--- /dev/null
+++ b/pkgs/servers/sql/postgresql/patches/socketdir-in-run.patch
@@ -0,0 +1,13 @@
+diff --git a/src/include/pg_config_manual.h b/src/include/pg_config_manual.h
+index 743401cb96..be5c5f61d2 100644
+--- a/src/include/pg_config_manual.h
++++ b/src/include/pg_config_manual.h
+@@ -179,7 +179,7 @@
+  * 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  "/run/postgresql"
+ 
+ /*
+  * This is the default event source for Windows event log.