diff --git a/Makefile b/Makefile
index 5dee20b..6096ac7 100644
--- a/Makefile
+++ b/Makefile
@@ -79,7 +79,7 @@ bios/int10.o: bios/int10.S bios/int10-real.S
 
 check: $(PROGRAM)
 	$(MAKE) -C tests
-	./$(PROGRAM) --dbgtest tests/pit/tick.bin
+	./$(PROGRAM) tests/pit/tick.bin
 .PHONY: check
 
 clean:
diff --git a/ioport.c b/ioport.c
index 42454d2..4bcc2b7 100644
--- a/ioport.c
+++ b/ioport.c
@@ -4,6 +4,7 @@
 
 #include <assert.h>
 #include <limits.h>
+#include <stdlib.h>
 #include <stdio.h>
 
 static uint8_t ioport_to_uint8(void *data)
@@ -28,6 +29,15 @@ static struct ioport_operations cmos_ram_rtc_ops = {
 	.io_out		= cmos_ram_rtc_io_out,
 };
 
+static bool debug_io_out(struct kvm *self, uint16_t port, void *data, int size, uint32_t count)
+{
+	exit(EXIT_SUCCESS);
+}
+
+static struct ioport_operations debug_ops = {
+	.io_out		= debug_io_out,
+};
+
 static bool dummy_io_in(struct kvm *self, uint16_t port, void *data, int size, uint32_t count)
 {
 	return true;
@@ -70,6 +80,10 @@ static struct ioport_operations *ioport_ops[USHRT_MAX] = {
 	[0x00A0]	= &dummy_read_write_ioport_ops,
 	[0x00A1]	= &dummy_read_write_ioport_ops,
 
+	/* PORT 00E0-00EF are 'motherboard specific' so we use them for our
+	   internal debugging purposes.  */
+	[0x00E0]	= &debug_ops,
+
 	/* PORT 00ED - DUMMY PORT FOR DELAY??? */
 	[0x00ED]	= &dummy_write_only_ioport_ops,
 
diff --git a/main.c b/main.c
index 9002c0f..91be735 100644
--- a/main.c
+++ b/main.c
@@ -10,11 +10,9 @@
 #include <string.h>
 #include <stdio.h>
 
-unsigned int dbgtest_mode;
-
 static void usage(char *argv[])
 {
-	fprintf(stderr, "  usage: %s [--dbgtest] [--single-step] [--kernel=]<kernel-image>\n",
+	fprintf(stderr, "  usage: %s [--single-step] [--kernel=]<kernel-image>\n",
 		argv[0]);
 	exit(1);
 }
@@ -55,9 +53,6 @@ int main(int argc, char *argv[])
 		} else if (option_matches(argv[i], "--params=")) {
 			kernel_cmdline = &argv[i][9];
 			continue;
-		} else if (option_matches(argv[i], "--dbgtest")) {
-			dbgtest_mode = 1;
-			continue;
 		} else if (option_matches(argv[i], "--single-step")) {
 			single_step = true;
 			continue;
@@ -137,13 +132,6 @@ int main(int argc, char *argv[])
 
 exit_kvm:
 
-	if (dbgtest_mode) {
-		if (kvm->kvm_run->exit_reason == KVM_EXIT_IO &&
-			kvm->kvm_run->io.port == 0xe0)
-			fprintf(stderr, "KVM: this is an expected IO error\n");
-			goto out;
-	}
-
 	fprintf(stderr, "KVM exit reason: %" PRIu32 " (\"%s\")\n",
 		kvm->kvm_run->exit_reason, kvm_exit_reasons[kvm->kvm_run->exit_reason]);
 	if (kvm->kvm_run->exit_reason == KVM_EXIT_UNKNOWN)