diff --git a/src/mame/drivers/megasys1.cpp b/src/mame/drivers/megasys1.cpp
index 9dc25ac8e1d..530120bc831 100644
--- a/src/mame/drivers/megasys1.cpp
+++ b/src/mame/drivers/megasys1.cpp
@@ -172,7 +172,7 @@ TIMER_DEVICE_CALLBACK_MEMBER(megasys1_state::megasys1A_scanline)
 {
 	int scanline = param;
 
-	// stdragon: irq 1 is vblank ("press start" behaviour), 2 unknown, 3 is RTE. Or maybe 1 is raster irq?
+	// stdragon: irq 1 is raster irq ("press start" behaviour), happens at around scanline 90(-16), 2 vblank, 3 is RTE. 
 	// p47: irq 2 valid, others RTE
 	// kickoff: irq 3 valid, others RTE
 	// tshingen: irq 3 RTE, irq 1 reads inputs, irq 2 sets vregs values (pending further investigation ...)
@@ -185,10 +185,10 @@ TIMER_DEVICE_CALLBACK_MEMBER(megasys1_state::megasys1A_scanline)
 	// soldam: irq 1 & 3 RTE, irq 2 valid
 	
 	if(scanline == 240) // vblank-out irq
-		m_maincpu->set_input_line(1, HOLD_LINE);
+		m_maincpu->set_input_line(2, HOLD_LINE);
 
 	if(scanline == 16)
-		m_maincpu->set_input_line(2, HOLD_LINE);
+		m_maincpu->set_input_line(1, HOLD_LINE);
 
 	if(scanline == 128)
 		m_maincpu->set_input_line(3, HOLD_LINE);