diff --git a/ioport.c b/ioport.c
index f78674d..d59436d 100644
--- a/ioport.c
+++ b/ioport.c
@@ -30,8 +30,21 @@ static struct ioport_operations cmos_ram_rtc_ops = {
 	.io_out		= cmos_ram_rtc_io_out,
 };
 
+static bool dummy_io_out(struct kvm *self, uint16_t port, void *data, int size, uint32_t count)
+{
+	return true;
+}
+
+static struct ioport_operations dummy_write_only_ioport_ops = {
+	.io_out		= dummy_io_out,
+};
+
 static struct ioport_operations *ioport_ops[USHRT_MAX] = {
 	[0x70]		= &cmos_ram_rtc_ops,
+
+	/* 0x00F0 - 0x00FF - Math co-processor */
+	[0xF0]		= &dummy_write_only_ioport_ops,
+	[0xF1]		= &dummy_write_only_ioport_ops,
 };
 
 static const char *to_direction(int direction)