diff --git a/stepmania/src/GameDef.cpp b/stepmania/src/GameDef.cpp
index 57e5aba681..c7281e77e1 100644
--- a/stepmania/src/GameDef.cpp
+++ b/stepmania/src/GameDef.cpp
@@ -20,7 +20,7 @@
 #include "InputMapper.h"
 #include "PrefsManager.h"
 
-GameButton GameDef::ButtonNameToIndex( const CString &sButtonName )
+GameButton GameDef::ButtonNameToIndex( const CString &sButtonName ) const
 {
 	for( int i=0; i<m_iButtonsPerController; i++ ) 
 		if( stricmp(m_szButtonNames[i], sButtonName) == 0 )
diff --git a/stepmania/src/GameDef.h b/stepmania/src/GameDef.h
index 89b0bd8e5f..3642ea834d 100644
--- a/stepmania/src/GameDef.h
+++ b/stepmania/src/GameDef.h
@@ -54,7 +54,7 @@ public:
 	GameButton	m_SecondaryMenuButton[NUM_MENU_BUTTONS];
 	int		m_iDefaultKeyboardKey[MAX_GAME_CONTROLLERS][MAX_GAME_BUTTONS];	// default keyboard keys only have an effect the current game is this game
 
-	GameButton ButtonNameToIndex( const CString &sButtonName );
+	GameButton ButtonNameToIndex( const CString &sButtonName ) const;
 	MenuInput GameInputToMenuInput( GameInput GameI ) const;
 	void MenuInputToGameInput( MenuInput MenuI, GameInput GameIout[4] ) const;
 };