diff --git a/hosts/linux/shared.nix b/hosts/linux/shared.nix
index ed8af77..d0f4ace 100644
--- a/hosts/linux/shared.nix
+++ b/hosts/linux/shared.nix
@@ -92,6 +92,9 @@
 
   # Common utilities across most Linux installs.
   environment.systemPackages = with pkgs; [
+    # Since not all applications are currently GTK 4,
+    # we need to manually add the Adwaita GTK 3 dark mode theme.
+    adw-gtk3
     firefox
     htop
     git