diff --git a/hw/char/serial.c b/hw/char/serial.c
index 824390817c..f11f2cdbf3 100644
--- a/hw/char/serial.c
+++ b/hw/char/serial.c
@@ -1033,7 +1033,7 @@ static uint64_t serial_mm_read(void *opaque, hwaddr addr,
                                unsigned size)
 {
     SerialMM *s = SERIAL_MM(opaque);
-    return serial_ioport_read(&s->serial, addr >> s->it_shift, 1);
+    return serial_ioport_read(&s->serial, addr >> s->regshift, 1);
 }
 
 static void serial_mm_write(void *opaque, hwaddr addr,
@@ -1041,7 +1041,7 @@ static void serial_mm_write(void *opaque, hwaddr addr,
 {
     SerialMM *s = SERIAL_MM(opaque);
     value &= 255;
-    serial_ioport_write(&s->serial, addr >> s->it_shift, value, 1);
+    serial_ioport_write(&s->serial, addr >> s->regshift, value, 1);
 }
 
 static void serial_mm_realize(DeviceState *dev, Error **errp)
@@ -1081,14 +1081,14 @@ static const MemoryRegionOps serial_mm_ops[3] = {
 };
 
 SerialMM *serial_mm_init(MemoryRegion *address_space,
-                         hwaddr base, int it_shift,
+                         hwaddr base, int regshift,
                          qemu_irq irq, int baudbase,
                          Chardev *chr, enum device_endian end)
 {
     SerialMM *smm = SERIAL_MM(qdev_create(NULL, TYPE_SERIAL_MM));
     SerialState *s = &smm->serial;
 
-    smm->it_shift = it_shift;
+    qdev_prop_set_uint8(DEVICE(smm), "regshift", regshift);
     s->irq = irq;
     qdev_prop_set_uint32(DEVICE(s), "baudbase", baudbase);
     qdev_prop_set_chr(DEVICE(s), "chardev", chr);
@@ -1097,7 +1097,7 @@ SerialMM *serial_mm_init(MemoryRegion *address_space,
     qdev_init_nofail(DEVICE(smm));
 
     memory_region_init_io(&s->io, NULL, &serial_mm_ops[end], smm,
-                          "serial", 8 << it_shift);
+                          "serial", 8 << regshift);
     memory_region_add_subregion(address_space, base, &s->io);
 
     return smm;
@@ -1111,10 +1111,21 @@ static void serial_mm_instance_init(Object *o)
                             TYPE_SERIAL, &error_abort, NULL);
 }
 
+static Property serial_mm_properties[] = {
+    /*
+     * Set the spacing between adjacent memory-mapped UART registers.
+     * Each register will be at (1 << regshift) bytes after the
+     * previous one.
+     */
+    DEFINE_PROP_UINT8("regshift", SerialMM, regshift, 0),
+    DEFINE_PROP_END_OF_LIST(),
+};
+
 static void serial_mm_class_init(ObjectClass *oc, void *data)
 {
     DeviceClass *dc = DEVICE_CLASS(oc);
 
+    dc->props = serial_mm_properties;
     dc->realize = serial_mm_realize;
 }
 
@@ -1124,6 +1135,7 @@ static const TypeInfo serial_mm_info = {
     .class_init = serial_mm_class_init,
     .instance_init = serial_mm_instance_init,
     .instance_size = sizeof(SerialMM),
+    .class_init = serial_mm_class_init,
 };
 
 static void serial_register_types(void)
diff --git a/include/hw/char/serial.h b/include/hw/char/serial.h
index 730165347c..eaeda62698 100644
--- a/include/hw/char/serial.h
+++ b/include/hw/char/serial.h
@@ -84,7 +84,7 @@ typedef struct SerialMM {
 
     SerialState serial;
 
-    int it_shift;
+    uint8_t regshift;
 } SerialMM;
 
 extern const VMStateDescription vmstate_serial;
@@ -101,7 +101,7 @@ void serial_set_frequency(SerialState *s, uint32_t frequency);
 SerialState *serial_init(int base, qemu_irq irq, int baudbase,
                          Chardev *chr, MemoryRegion *system_io);
 SerialMM *serial_mm_init(MemoryRegion *address_space,
-                         hwaddr base, int it_shift,
+                         hwaddr base, int regshift,
                          qemu_irq irq, int baudbase,
                          Chardev *chr, enum device_endian end);