diff --git a/src/mame/includes/deco32.h b/src/mame/includes/deco32.h
index e95c7a47be8..2da91b5b6a2 100644
--- a/src/mame/includes/deco32.h
+++ b/src/mame/includes/deco32.h
@@ -8,7 +8,7 @@ public:
 		m_decobsmt(*this, "decobsmt")
     { }
 
-	required_device<decobsmt_device> m_decobsmt;
+	optional_device<decobsmt_device> m_decobsmt;
 
 	UINT32 *m_ram;
 	int m_raster_enable;