diff --git a/src/mame/drivers/slotcarn.c b/src/mame/drivers/slotcarn.c
index 3a626fc24d4..e83c0f6b34c 100644
--- a/src/mame/drivers/slotcarn.c
+++ b/src/mame/drivers/slotcarn.c
@@ -148,7 +148,7 @@ static MC6845_UPDATE_ROW( update_row )
 				col |= 0x03;
 
 			col = state->m_ram_palette[col & 0x3ff];
-			bitmap.pix32(y, x) = pens[col ? col : (lscnblk ? 8 : 0)];
+			bitmap.pix32(y, x) = pens[col ? col & (NUM_PENS-1) : (lscnblk ? 8 : 0)];
 
 			x++;
 		}