diff --git a/src/emu/video/tms9928a.c b/src/emu/video/tms9928a.c
index a98836b80f6..4702e6f028a 100644
--- a/src/emu/video/tms9928a.c
+++ b/src/emu/video/tms9928a.c
@@ -300,7 +300,7 @@ void tms9928a_device::device_timer(emu_timer &timer, device_timer_id id, int par
 		for ( int i = 0; i < TMS9928A_TOTAL_HORZ; i++ )
 			p[i] = BackColour;
 
-		/* vblank is set 1 line after end of active display */
+		/* vblank is set at the last cycle of the first inactive line */
 		if ( y == 193 )
 		{
 			m_StatusReg |= 0x80;
@@ -581,7 +581,7 @@ void tms9928a_device::device_timer(emu_timer &timer, device_timer_id id, int par
 	}
 
 	/* Schedule next callback */
-	m_line_timer->adjust( m_screen->time_until_pos( ( raw_vpos + 1 ) % m_screen->height() , 0 ) );
+	m_line_timer->adjust( m_screen->time_until_pos( ( raw_vpos + 1 ) % m_screen->height() , TMS9928A_HORZ_DISPLAY_START ) );
 }
 
 
@@ -672,6 +672,6 @@ void tms9928a_device::device_reset()
 	m_latch = 0;
 	m_mode = 0;
 
-	m_line_timer->adjust( m_screen->time_until_pos( 0, 0 ) );
+	m_line_timer->adjust( m_screen->time_until_pos( 0, TMS9928A_HORZ_DISPLAY_START ) );
 }