diff --git a/src/mame/drivers/zorba.cpp b/src/mame/drivers/zorba.cpp
index 4e4f7bc186b..af9a26ad301 100644
--- a/src/mame/drivers/zorba.cpp
+++ b/src/mame/drivers/zorba.cpp
@@ -372,7 +372,7 @@ template <unsigned N> WRITE_LINE_MEMBER( zorba_state::irq_w )
 	else if (BIT(m_irq, 3)) vector = 0x88;
 	else                    vector = 0x84; // very wrong, need test cases for other things
 
-	m_maincpu->set_input_line_and_vector(INPUT_LINE_IRQ0, m_irq, vector); // Z80
+	m_maincpu->set_input_line_and_vector(INPUT_LINE_IRQ0, m_irq ? ASSERT_LINE : CLEAR_LINE, vector); // Z80
 }