diff --git a/retro-core/components/smsplus/cpu/z80.c b/retro-core/components/smsplus/cpu/z80.c
index 8252e8f50..193119115 100644
--- a/retro-core/components/smsplus/cpu/z80.c
+++ b/retro-core/components/smsplus/cpu/z80.c
@@ -1180,7 +1180,7 @@ static void dummy_write(UINT16 addr, UINT8 val)
   //
 }
 
-static UINT16 dummy_irq(UINT8 param)
+static int dummy_irq(int param)
 {
   return 0xFF;
 }