diff --git a/nixos/modules/services/x11/xserver.nix b/nixos/modules/services/x11/xserver.nix
index d42d7caaa06b..6e470e65e351 100644
--- a/nixos/modules/services/x11/xserver.nix
+++ b/nixos/modules/services/x11/xserver.nix
@@ -527,6 +527,11 @@ in
           '';
 
         script = "${cfg.displayManager.job.execCmd}";
+
+        serviceConfig = {
+          Restart = "always";
+          RestartSec = "200ms";
+        };
       };
 
     services.xserver.displayManager.xserverArgs =
diff --git a/pkgs/applications/display-managers/slim/default.nix b/pkgs/applications/display-managers/slim/default.nix
index 750efdc6ea4c..0b5bcccfb21a 100644
--- a/pkgs/applications/display-managers/slim/default.nix
+++ b/pkgs/applications/display-managers/slim/default.nix
@@ -13,6 +13,11 @@ stdenv.mkDerivation rec {
     [ # Allow the paths of the configuration file and theme directory to
       # be set at runtime.
       ./runtime-paths.patch
+
+      # Exit after the user's session has finished.  This works around
+      # slim's broken PAM session handling (see
+      # http://developer.berlios.de/bugs/?func=detailbug&bug_id=19102&group_id=2663).
+      ./run-once.patch
     ];
 
   preConfigure = "substituteInPlace CMakeLists.txt --replace /etc $out/etc --replace /lib $out/lib";
diff --git a/pkgs/applications/display-managers/slim/run-once.patch b/pkgs/applications/display-managers/slim/run-once.patch
new file mode 100644
index 000000000000..78f1454a883e
--- /dev/null
+++ b/pkgs/applications/display-managers/slim/run-once.patch
@@ -0,0 +1,12 @@
+diff -ru -x '*~' slim-1.3.6-orig/app.cpp slim-1.3.6/app.cpp
+--- slim-1.3.6-orig/app.cpp	2013-10-15 11:02:55.629263422 +0200
++++ slim-1.3.6/app.cpp	2013-10-15 13:00:10.141210784 +0200
+@@ -816,7 +822,7 @@
+ 	StopServer();
+ 	RemoveLock();
+ 	while (waitpid(-1, NULL, WNOHANG) > 0); /* Collects all dead childrens */
+-	Run();
++	exit(OK_EXIT);
+ }
+ 
+ void App::KillAllClients(Bool top) {