diff --git a/nixos/modules/programs/tmux.nix b/nixos/modules/programs/tmux.nix
index 3d5a37274ae2..ed077e3daa76 100644
--- a/nixos/modules/programs/tmux.nix
+++ b/nixos/modules/programs/tmux.nix
@@ -177,7 +177,7 @@ in {
       systemPackages = [ pkgs.tmux ];
 
       variables = {
-        TMUX_TMPDIR = lib.optional cfg.secureSocket ''''${XDG_RUNTIME_DIR:-"/run/user/\$(id -u)"}'';
+        TMUX_TMPDIR = lib.optional cfg.secureSocket ''''${XDG_RUNTIME_DIR:-"/run/user/$(id -u)"}'';
       };
     };
   };