diff --git a/nixos/modules/programs/gamemode.nix b/nixos/modules/programs/gamemode.nix
index 14892f9c6eac..bd3248c1c5a2 100644
--- a/nixos/modules/programs/gamemode.nix
+++ b/nixos/modules/programs/gamemode.nix
@@ -2,7 +2,7 @@
 
 let
   cfg = config.programs.gamemode;
-  settingsFormat = pkgs.formats.ini { };
+  settingsFormat = pkgs.formats.ini { listsAsDuplicateKeys = true; };
   configFile = settingsFormat.generate "gamemode.ini" cfg.settings;
 in
 {