diff --git a/src/mess/drivers/spectrum.c b/src/mess/drivers/spectrum.c
index 163308645ff..f32f95c6ec5 100644
--- a/src/mess/drivers/spectrum.c
+++ b/src/mess/drivers/spectrum.c
@@ -645,10 +645,15 @@ static GFXDECODE_START( spectrum )
 	GFXDECODE_ENTRY( "maincpu", 0x3d00, spectrum_charlayout, 0, 8 )
 GFXDECODE_END
 
+void spectrum_state::device_timer(emu_timer &timer, device_timer_id id, int param, void *ptr)
+{
+	m_maincpu->set_input_line(0, CLEAR_LINE);
+}
 
 INTERRUPT_GEN_MEMBER(spectrum_state::spec_interrupt)
 {
-	device.execute().set_input_line(0, HOLD_LINE);
+	m_maincpu->set_input_line(0, HOLD_LINE);
+	timer_set(attotime::from_ticks(32, m_maincpu->clock()), 0, 0);
 }
 
 DEVICE_IMAGE_LOAD_MEMBER(spectrum_state, spectrum_cart)
diff --git a/src/mess/includes/spectrum.h b/src/mess/includes/spectrum.h
index dd86e8f242b..25064cffbd7 100644
--- a/src/mess/includes/spectrum.h
+++ b/src/mess/includes/spectrum.h
@@ -242,6 +242,7 @@ protected:
 	void ts2068_hires_scanline(bitmap_ind16 &bitmap, int y, int borderlines);
 	void ts2068_64col_scanline(bitmap_ind16 &bitmap, int y, int borderlines, unsigned short inkcolor);
 	void ts2068_lores_scanline(bitmap_ind16 &bitmap, int y, int borderlines, int screen);
+	virtual void device_timer(emu_timer &timer, device_timer_id id, int param, void *ptr);
 };
 
 
diff --git a/src/mess/video/spectrum.c b/src/mess/video/spectrum.c
index d3640db4ce6..a39699c758b 100644
--- a/src/mess/video/spectrum.c
+++ b/src/mess/video/spectrum.c
@@ -21,7 +21,7 @@
 ***************************************************************************/
 VIDEO_START_MEMBER(spectrum_state,spectrum)
 {
-	m_frame_invert_count = 25;
+	m_frame_invert_count = 16;
 	m_frame_number = 0;
 	m_flash_invert = 0;
 
@@ -37,7 +37,7 @@ VIDEO_START_MEMBER(spectrum_state,spectrum)
 
 VIDEO_START_MEMBER(spectrum_state,spectrum_128)
 {
-	m_frame_invert_count = 25;
+	m_frame_invert_count = 16;
 	m_frame_number = 0;
 	m_flash_invert = 0;