diff --git a/nixos/modules/services/x11/desktop-managers/gnome3.nix b/nixos/modules/services/x11/desktop-managers/gnome3.nix
index a36a47d376b..671301246a8 100644
--- a/nixos/modules/services/x11/desktop-managers/gnome3.nix
+++ b/nixos/modules/services/x11/desktop-managers/gnome3.nix
@@ -118,6 +118,7 @@ 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.