diff --git a/hw/debugcon.c b/hw/debugcon.c
index 14f83f1962..e8a855e33a 100644
--- a/hw/debugcon.c
+++ b/hw/debugcon.c
@@ -29,20 +29,27 @@
 #include "isa.h"
 #include "pc.h"
 
+#define TYPE_ISA_DEBUGCON_DEVICE "isa-debugcon"
+#define ISA_DEBUGCON_DEVICE(obj) \
+     OBJECT_CHECK(ISADebugconState, (obj), TYPE_ISA_DEBUGCON_DEVICE)
+
 //#define DEBUG_DEBUGCON
 
 typedef struct DebugconState {
+    MemoryRegion io;
     CharDriverState *chr;
     uint32_t readback;
 } DebugconState;
 
 typedef struct ISADebugconState {
-    ISADevice dev;
+    ISADevice parent_obj;
+
     uint32_t iobase;
     DebugconState state;
 } ISADebugconState;
 
-static void debugcon_ioport_write(void *opaque, uint32_t addr, uint32_t val)
+static void debugcon_ioport_write(void *opaque, hwaddr addr, uint64_t val,
+                                  unsigned width)
 {
     DebugconState *s = opaque;
     unsigned char ch = val;
@@ -55,7 +62,7 @@ static void debugcon_ioport_write(void *opaque, uint32_t addr, uint32_t val)
 }
 
 
-static uint32_t debugcon_ioport_read(void *opaque, uint32_t addr)
+static uint64_t debugcon_ioport_read(void *opaque, hwaddr addr, unsigned width)
 {
     DebugconState *s = opaque;
 
@@ -66,6 +73,14 @@ static uint32_t debugcon_ioport_read(void *opaque, uint32_t addr)
     return s->readback;
 }
 
+static const MemoryRegionOps debugcon_ops = {
+    .read = debugcon_ioport_read,
+    .write = debugcon_ioport_write,
+    .valid.min_access_size = 1,
+    .valid.max_access_size = 1,
+    .endianness = DEVICE_LITTLE_ENDIAN,
+};
+
 static void debugcon_init_core(DebugconState *s)
 {
     if (!s->chr) {
@@ -78,12 +93,14 @@ static void debugcon_init_core(DebugconState *s)
 
 static int debugcon_isa_initfn(ISADevice *dev)
 {
-    ISADebugconState *isa = DO_UPCAST(ISADebugconState, dev, dev);
+    ISADebugconState *isa = ISA_DEBUGCON_DEVICE(dev);
     DebugconState *s = &isa->state;
 
     debugcon_init_core(s);
-    register_ioport_write(isa->iobase, 1, 1, debugcon_ioport_write, s);
-    register_ioport_read(isa->iobase, 1, 1, debugcon_ioport_read, s);
+    memory_region_init_io(&s->io, &debugcon_ops, s,
+                          TYPE_ISA_DEBUGCON_DEVICE, 1);
+    memory_region_add_subregion(isa_address_space_io(dev),
+                                isa->iobase, &s->io);
     return 0;
 }
 
@@ -103,7 +120,7 @@ static void debugcon_isa_class_initfn(ObjectClass *klass, void *data)
 }
 
 static TypeInfo debugcon_isa_info = {
-    .name          = "isa-debugcon",
+    .name          = TYPE_ISA_DEBUGCON_DEVICE,
     .parent        = TYPE_ISA_DEVICE,
     .instance_size = sizeof(ISADebugconState),
     .class_init    = debugcon_isa_class_initfn,