diff --git a/src/mame/machine/smpc.c b/src/mame/machine/smpc.c
index da92fba704a..27b3bd9e9a5 100644
--- a/src/mame/machine/smpc.c
+++ b/src/mame/machine/smpc.c
@@ -316,6 +316,7 @@ static TIMER_CALLBACK( stv_smpc_intback )
 		state->m_scu.ist |= (IRQ_SMPC);
 
 	/* clear hand-shake flag */
+	state->m_smpc_ram[0x5f] = 0x10;
 	state->m_smpc_ram[0x63] = 0x00;
 }