diff --git a/src/modules/wlr/taskbar.cpp b/src/modules/wlr/taskbar.cpp
index 6dd24a73..95a7a512 100644
--- a/src/modules/wlr/taskbar.cpp
+++ b/src/modules/wlr/taskbar.cpp
@@ -86,11 +86,13 @@ static bool image_load_icon(Gtk::Image& image, Glib::RefPtr<Gtk::IconTheme> icon
      * send a single app-id, but in any case this works fine */
     while (stream >> app_id)
     {
-        std::transform(app_id.begin(), app_id.end(), lower_app_id.begin(),
-            [](char c){ return std::tolower(c); });
         std::string icon_name = get_from_icon_theme(icon_theme, app_id);
-        if (icon_name.empty())
+        if (icon_name.empty()) {
+            lower_app_id = app_id;
+            std::transform(lower_app_id.begin(), lower_app_id.end(), lower_app_id.begin(),
+                    [](char c){ return std::tolower(c); });
             icon_name = get_from_icon_theme(icon_theme, lower_app_id);
+        }
 
         if (icon_name.empty())
             icon_name = get_from_desktop_app_info(app_id);