diff --git a/src/modules/sway/window.cpp b/src/modules/sway/window.cpp
index 2b62da14..f005bd14 100644
--- a/src/modules/sway/window.cpp
+++ b/src/modules/sway/window.cpp
@@ -43,7 +43,9 @@ void Window::onCmd(const struct Ipc::ipc_response& res) {
     auto output = payload["output"].isString() ? payload["output"].asString() : "";
     std::tie(app_nb_, floating_count_, windowId_, window_, app_id_, app_class_, shell_, layout_,
              marks_) = getFocusedNode(payload["nodes"], output);
-    updateAppIconName(app_id_, app_class_);
+    // Do not resolve the app icon here: onCmd runs on the sway IPC worker thread and
+    // updateAppIconName() touches the global Gtk::IconTheme cache, which is not thread-safe.
+    // The icon is resolved in update() on the main thread instead (triggered by dp.emit()).
     dp.emit();
   } catch (const std::exception& e) {
     spdlog::error("Window: {}", e.what());
@@ -102,6 +104,9 @@ auto Window::update() -> void {
     setTooltipMarkup(window_);
   }
 
+  // Resolve the app icon on the main thread to avoid racing with GTK draw on the
+  // global Gtk::IconTheme cache (see onCmd).
+  updateAppIconName(app_id_, app_class_);
   updateAppIcon();
 
   // Call parent update