diff --git a/stepmania/src/DifficultyIcon.cpp b/stepmania/src/DifficultyIcon.cpp
index 44d97e1eec..b8ba2961c3 100644
--- a/stepmania/src/DifficultyIcon.cpp
+++ b/stepmania/src/DifficultyIcon.cpp
@@ -10,6 +10,7 @@
 -----------------------------------------------------------------------------
 */
 
+/* Obsolete: use DifficultyClass. */
 #include "DifficultyIcon.h"
 #include "RageUtil.h"
 #include "GameConstantsAndTypes.h"