diff --git a/nixos/modules/services/mail/dovecot.nix b/nixos/modules/services/mail/dovecot.nix
index b42c73b8666..543e732127a 100644
--- a/nixos/modules/services/mail/dovecot.nix
+++ b/nixos/modules/services/mail/dovecot.nix
@@ -30,6 +30,7 @@ let
 
     ''
       default_internal_user = ${cfg.user}
+      default_internal_group = ${cfg.group}
       ${optionalString (cfg.mailUser != null) "mail_uid = ${cfg.mailUser}"}
       ${optionalString (cfg.mailGroup != null) "mail_gid = ${cfg.mailGroup}"}
 
diff --git a/pkgs/servers/mail/dovecot/default.nix b/pkgs/servers/mail/dovecot/default.nix
index 0060a59d807..c9065d04161 100644
--- a/pkgs/servers/mail/dovecot/default.nix
+++ b/pkgs/servers/mail/dovecot/default.nix
@@ -8,7 +8,7 @@
 }:
 
 stdenv.mkDerivation rec {
-  name = "dovecot-2.3.0.1";
+  name = "dovecot-2.3.1";
 
   nativeBuildInputs = [ perl pkgconfig ];
   buildInputs =
@@ -20,7 +20,7 @@ stdenv.mkDerivation rec {
 
   src = fetchurl {
     url = "http://dovecot.org/releases/2.3/${name}.tar.gz";
-    sha256 = "0lzisrdgrj5qqwjb7bv99mf2aljm568r6g108yisp0s644z2nxxb";
+    sha256 = "14zva4f8k64x86sm9n21cp2yvrpph6k6k52bm22a00pxjwdq50q8";
   };
 
   preConfigure = ''
diff --git a/pkgs/servers/mail/dovecot/plugins/pigeonhole/default.nix b/pkgs/servers/mail/dovecot/plugins/pigeonhole/default.nix
index 92b404d0f65..af9ff3b257b 100644
--- a/pkgs/servers/mail/dovecot/plugins/pigeonhole/default.nix
+++ b/pkgs/servers/mail/dovecot/plugins/pigeonhole/default.nix
@@ -2,11 +2,11 @@
 
 stdenv.mkDerivation rec {
   name = "dovecot-pigeonhole-${version}";
-  version = "0.5.0.1";
+  version = "0.5.1";
 
   src = fetchurl {
     url = "http://pigeonhole.dovecot.org/releases/2.3/dovecot-2.3-pigeonhole-${version}.tar.gz";
-    sha256 = "1lpsdqh9pwqx917z5v23bahhhbrcb3y5ps3l413sli8cn4a6sdan";
+    sha256 = "0ivmaxic6cygfphvlrvy0xgggydm7j7kjv1ssfqbr08q4rcsmc73";
   };
 
   buildInputs = [ dovecot openssl ];