diff --git a/imgui_demo.cpp b/imgui_demo.cpp
index eb15dcd1e..3fd05ba0e 100644
--- a/imgui_demo.cpp
+++ b/imgui_demo.cpp
@@ -8099,6 +8099,9 @@ void ImGui::ShowAboutWindow(bool* p_open)
         ImGui::Separator();
         ImGui::Text("sizeof(size_t): %d, sizeof(ImDrawIdx): %d, sizeof(ImDrawVert): %d", (int)sizeof(size_t), (int)sizeof(ImDrawIdx), (int)sizeof(ImDrawVert));
         ImGui::Text("define: __cplusplus=%d", (int)__cplusplus);
+#ifdef IMGUI_ENABLE_TEST_ENGINE
+        ImGui::Text("define: IMGUI_ENABLE_TEST_ENGINE");
+#endif
 #ifdef IMGUI_DISABLE_OBSOLETE_FUNCTIONS
         ImGui::Text("define: IMGUI_DISABLE_OBSOLETE_FUNCTIONS");
 #endif