diff --git a/modules/services/networking/quassel.nix b/modules/services/networking/quassel.nix
index 591bd6e6ce22..7e6ad5c8e813 100644
--- a/modules/services/networking/quassel.nix
+++ b/modules/services/networking/quassel.nix
@@ -5,6 +5,7 @@ with pkgs.lib;
 let
   quassel = pkgs.quasselDaemon;
   cfg = config.services.quassel;
+  user = if cfg.user != null then cfg.user else "quassel";
 in
 
 {
@@ -39,16 +40,16 @@ in
       };
 
       dataDir = mkOption {
-        default = ''/home/${cfg.user}/.config/quassel-irc.org'';
+        default = ''/home/${user}/.config/quassel-irc.org'';
         description = ''
           The directory holding configuration files, the SQlite database and the SSL Cert.
         '';
       };
 
       user = mkOption {
-        default = "quassel";
+        default = null;
         description = ''
-          The user the Quassel daemon should run as.
+          The existing user the Quassel daemon should run as. If left empty, a default "quassel" user will be created.
         '';
       };
 
@@ -61,10 +62,10 @@ in
 
   config = mkIf cfg.enable {
 
-    users.extraUsers = singleton
+    users.extraUsers = mkIf (cfg.user == null) [
       { name = cfg.user;
         description = "Quassel IRC client daemon";
-      };
+      }];
     
 
     jobs.quassel =
@@ -74,11 +75,11 @@ in
 
         preStart = ''
             mkdir -p ${cfg.dataDir}
-            chown ${cfg.user} ${cfg.dataDir}
+            chown ${user} ${cfg.dataDir}
         '';
 
         exec = ''
-            ${pkgs.su}/bin/su -s ${pkgs.stdenv.shell} ${cfg.user} \
+            ${pkgs.su}/bin/su -s ${pkgs.stdenv.shell} ${user} \
                 -c '${quassel}/bin/quasselcore --listen=${cfg.interface}\
                     --port=${toString cfg.portNumber} --configdir=${cfg.dataDir}'
         '';