diff --git a/stepmania/src/GameState.cpp b/stepmania/src/GameState.cpp
index ca50e51272..b98ed0210f 100644
--- a/stepmania/src/GameState.cpp
+++ b/stepmania/src/GameState.cpp
@@ -1588,7 +1588,7 @@ void GameState::VisitAttractScreen( const RString sScreenName )
 		m_iNumTimesThroughAttract++;
 }
 
-bool GameState::DifficultiesLocked()
+bool GameState::DifficultiesLocked() const
 {
  	if( m_PlayMode == PLAY_MODE_RAVE )
 		return true;
diff --git a/stepmania/src/GameState.h b/stepmania/src/GameState.h
index 813f5459db..91eb9328da 100644
--- a/stepmania/src/GameState.h
+++ b/stepmania/src/GameState.h
@@ -62,7 +62,7 @@ public:
 	int					m_iCoins;			// not "credits"
 	PlayerNumber				m_MasterPlayerNumber;		// used in Styles where one player controls both sides
 	bool					m_bMultiplayer;
-	bool DifficultiesLocked();
+	bool DifficultiesLocked() const;
 	bool ChangePreferredDifficulty( PlayerNumber pn, Difficulty dc );
 	bool ChangePreferredDifficulty( PlayerNumber pn, int dir );
 	bool ChangePreferredCourseDifficulty( PlayerNumber pn, CourseDifficulty cd );