diff --git a/nixos/modules/services/x11/desktop-managers/pantheon.nix b/nixos/modules/services/x11/desktop-managers/pantheon.nix
index cf02a71248b..195da75e744 100644
--- a/nixos/modules/services/x11/desktop-managers/pantheon.nix
+++ b/nixos/modules/services/x11/desktop-managers/pantheon.nix
@@ -42,6 +42,7 @@ in
 
       sessionPath = mkOption {
         default = [];
+        type = types.listOf types.package;
         example = literalExample "[ pkgs.gnome3.gpaste ]";
         description = ''
           Additional list of packages to be added to the session search path.