diff --git a/nixos/doc/manual/release-notes/rl-1909.xml b/nixos/doc/manual/release-notes/rl-1909.xml
index 58ab7207f53..9aa992766a2 100644
--- a/nixos/doc/manual/release-notes/rl-1909.xml
+++ b/nixos/doc/manual/release-notes/rl-1909.xml
@@ -33,6 +33,13 @@
      PHP 7.1 is no longer supported due to upstream not supporting this version for the entire lifecycle of the 19.09 release.
     </para>
    </listitem>
+   <listitem>
+    <para>
+     Postgresql for NixOS service now defaults to v11. <literal>pkgs.postgresql</literal> is still 9.6, but
+     may be updated in future release. To prevent future update problems replace <literal>pkgs.postgresql</literal>
+     with an explicitly versioned <literal>pkgs.postgresql_9_6</literal>.
+    </para>
+   </listitem>
    <listitem>
      <para>
        The binfmt module is now easier to use. Additional systems can
diff --git a/nixos/modules/services/databases/postgresql.nix b/nixos/modules/services/databases/postgresql.nix
index 7bba4dacddc..a19eb820a9c 100644
--- a/nixos/modules/services/databases/postgresql.nix
+++ b/nixos/modules/services/databases/postgresql.nix
@@ -226,7 +226,8 @@ in
       # Note: when changing the default, make it conditional on
       # ‘system.stateVersion’ to maintain compatibility with existing
       # systems!
-      mkDefault (if versionAtLeast config.system.stateVersion "17.09" then pkgs.postgresql_9_6
+      mkDefault (if versionAtLeast config.system.stateVersion "19.09" then pkgs.postgresql_11
+            else if versionAtLeast config.system.stateVersion "17.09" then pkgs.postgresql_9_6
             else if versionAtLeast config.system.stateVersion "16.03" then pkgs.postgresql_9_5
             else throw "postgresql_9_4 was removed, please upgrade your postgresql version.");