diff --git a/stepmania/src/EnumHelper.cpp b/stepmania/src/EnumHelper.cpp
index 06d6b4a0e5..bda233d950 100644
--- a/stepmania/src/EnumHelper.cpp
+++ b/stepmania/src/EnumHelper.cpp
@@ -3,10 +3,16 @@
 #include "LuaManager.h"
 #include "RageUtil.h"
 
-int CheckEnum( lua_State *L, LuaReference &table, int iPos, int iInvalid, const char *szType )
+int CheckEnum( lua_State *L, LuaReference &table, int iPos, int iInvalid, const char *szType, bool bAllowInvalid )
 {
 	if( lua_isnil(L, iPos) )
-		return iInvalid;
+	{
+		if( bAllowInvalid )
+			return iInvalid;
+
+		LuaHelpers::Push( L, ssprintf("Expected %s; got nil", szType) );
+		lua_error( L );
+	}
 
 	iPos = LuaHelpers::AbsIndex( L, iPos );
 
diff --git a/stepmania/src/EnumHelper.h b/stepmania/src/EnumHelper.h
index cb7ddc9d22..1e8fd4053b 100644
--- a/stepmania/src/EnumHelper.h
+++ b/stepmania/src/EnumHelper.h
@@ -12,7 +12,7 @@ extern "C"
 #define FOREACH_ENUM_N( e, max, var )	for( e var=(e)0; var<max; enum_add<e>( var, +1 ) )
 #define FOREACH_ENUM( e, var )	for( e var=(e)0; var<NUM_##e; enum_add<e>( var, +1 ) )
 
-int CheckEnum( lua_State *L, LuaReference &table, int iPos, int iInvalid, const char *szType );
+int CheckEnum( lua_State *L, LuaReference &table, int iPos, int iInvalid, const char *szType, bool bAllowInvalid );
 
 template<typename T>
 struct EnumTraits
@@ -28,9 +28,9 @@ template<typename T> LuaReference EnumTraits<T>::EnumToString;
 namespace Enum
 {
 	template<typename T>
-	static T Check( lua_State *L, int iPos )
+	static T Check( lua_State *L, int iPos, bool bAllowInvalid = false )
 	{
-		return (T) CheckEnum( L, EnumTraits<T>::StringToEnum, iPos, EnumTraits<T>::Invalid, EnumTraits<T>::szName );
+		return (T) CheckEnum( L, EnumTraits<T>::StringToEnum, iPos, EnumTraits<T>::Invalid, EnumTraits<T>::szName, bAllowInvalid );
 	}
 	template<typename T>
 	static void Push( lua_State *L, T iVal )