diff --git a/.config/linux/system/module/Gnome.nix b/.config/linux/system/module/Gnome.nix
index 04645b3..faaad62 100644
--- a/.config/linux/system/module/Gnome.nix
+++ b/.config/linux/system/module/Gnome.nix
@@ -10,6 +10,12 @@ in {
 		options = "grp:caps_toggle,lv3:ralt_switch";
 	};
 
+	# Specify default apps.
+	xdg.mime.defaultApplications = {
+		"image/png"  = "org.gnome.Loupe.desktop";
+		"image/jpeg" = "org.gnome.Loupe.desktop";
+	};
+
 	# Disable some apps.
 	services.gnome.gnome-keyring.enable = lib.mkForce false;
 	environment.gnome.excludePackages = with pkgs.gnome; [