diff --git a/hw/arm/bcm2835_peripherals.c b/hw/arm/bcm2835_peripherals.c
index cca5b5ad04..188b112c13 100644
--- a/hw/arm/bcm2835_peripherals.c
+++ b/hw/arm/bcm2835_peripherals.c
@@ -27,8 +27,7 @@ static void create_unimp(BCM2835PeripheralState *ps,
                          UnimplementedDeviceState *uds,
                          const char *name, hwaddr ofs, hwaddr size)
 {
-    sysbus_init_child_obj(OBJECT(ps), name, uds,
-                          sizeof(UnimplementedDeviceState),
+    sysbus_init_child_obj(OBJECT(ps), name, uds, sizeof(*uds),
                           TYPE_UNIMPLEMENTED_DEVICE);
     qdev_prop_set_string(DEVICE(uds), "name", name);
     qdev_prop_set_uint64(DEVICE(uds), "size", size);
diff --git a/hw/arm/mps2-tz.c b/hw/arm/mps2-tz.c
index 8a050228d0..ad0bc9365a 100644
--- a/hw/arm/mps2-tz.c
+++ b/hw/arm/mps2-tz.c
@@ -174,8 +174,7 @@ static MemoryRegion *make_unimp_dev(MPS2TZMachineState *mms,
      */
     UnimplementedDeviceState *uds = opaque;
 
-    sysbus_init_child_obj(OBJECT(mms), name, uds,
-                          sizeof(UnimplementedDeviceState),
+    sysbus_init_child_obj(OBJECT(mms), name, uds, sizeof(*uds),
                           TYPE_UNIMPLEMENTED_DEVICE);
     qdev_prop_set_string(DEVICE(uds), "name", name);
     qdev_prop_set_uint64(DEVICE(uds), "size", size);
@@ -552,7 +551,7 @@ static void mps2tz_common_init(MachineState *machine)
         char *gpioname;
 
         sysbus_init_child_obj(OBJECT(machine), ppcinfo->name, ppc,
-                              sizeof(TZPPC), TYPE_TZ_PPC);
+                              sizeof(*ppc), TYPE_TZ_PPC);
         ppcdev = DEVICE(ppc);
 
         for (port = 0; port < TZ_NUM_PORTS; port++) {
diff --git a/hw/arm/musca.c b/hw/arm/musca.c
index cd7df7c191..b7f1c4e128 100644
--- a/hw/arm/musca.c
+++ b/hw/arm/musca.c
@@ -142,8 +142,7 @@ static MemoryRegion *make_unimp_dev(MuscaMachineState *mms,
      */
     UnimplementedDeviceState *uds = opaque;
 
-    sysbus_init_child_obj(OBJECT(mms), name, uds,
-                          sizeof(UnimplementedDeviceState),
+    sysbus_init_child_obj(OBJECT(mms), name, uds, sizeof(*uds),
                           TYPE_UNIMPLEMENTED_DEVICE);
     qdev_prop_set_string(DEVICE(uds), "name", name);
     qdev_prop_set_uint64(DEVICE(uds), "size", size);
@@ -246,8 +245,7 @@ static MemoryRegion *make_mpc(MuscaMachineState *mms, void *opaque,
     case MPC_CRYPTOISLAND:
         /* We don't implement the CryptoIsland yet */
         uds = &mms->cryptoisland;
-        sysbus_init_child_obj(OBJECT(mms), name, uds,
-                              sizeof(UnimplementedDeviceState),
+        sysbus_init_child_obj(OBJECT(mms), name, uds, sizeof(*uds),
                               TYPE_UNIMPLEMENTED_DEVICE);
         qdev_prop_set_string(DEVICE(uds), "name", mpcinfo[i].name);
         qdev_prop_set_uint64(DEVICE(uds), "size", mpcinfo[i].size);
@@ -535,7 +533,7 @@ static void musca_init(MachineState *machine)
         char *gpioname;
 
         sysbus_init_child_obj(OBJECT(machine), ppcinfo->name, ppc,
-                              sizeof(TZPPC), TYPE_TZ_PPC);
+                              sizeof(*ppc), TYPE_TZ_PPC);
         ppcdev = DEVICE(ppc);
 
         for (port = 0; port < TZ_NUM_PORTS; port++) {
diff --git a/hw/display/sm501.c b/hw/display/sm501.c
index 3e62eca3de..ccdbce1a06 100644
--- a/hw/display/sm501.c
+++ b/hw/display/sm501.c
@@ -2023,7 +2023,7 @@ static void sm501_sysbus_init(Object *o)
     SM501SysBusState *sm501 = SYSBUS_SM501(o);
     SerialMM *smm = &sm501->serial;
 
-    sysbus_init_child_obj(o, "serial", smm, sizeof(SerialMM), TYPE_SERIAL_MM);
+    sysbus_init_child_obj(o, "serial", smm, sizeof(*smm), TYPE_SERIAL_MM);
     qdev_set_legacy_instance_id(DEVICE(smm), SM501_UART0, 2);
     qdev_prop_set_uint8(DEVICE(smm), "regshift", 2);
     qdev_prop_set_uint8(DEVICE(smm), "endianness", DEVICE_LITTLE_ENDIAN);
diff --git a/hw/microblaze/xlnx-zynqmp-pmu.c b/hw/microblaze/xlnx-zynqmp-pmu.c
index bd56eccd66..30ad133ec3 100644
--- a/hw/microblaze/xlnx-zynqmp-pmu.c
+++ b/hw/microblaze/xlnx-zynqmp-pmu.c
@@ -69,8 +69,8 @@ static void xlnx_zynqmp_pmu_soc_init(Object *obj)
     /* Create the IPI device */
     for (int i = 0; i < XLNX_ZYNQMP_PMU_NUM_IPIS; i++) {
         char *name = g_strdup_printf("ipi%d", i);
-        sysbus_init_child_obj(obj, name, &s->ipi[i],
-                              sizeof(XlnxZynqMPIPI), TYPE_XLNX_ZYNQMP_IPI);
+        sysbus_init_child_obj(obj, name, &s->ipi[i], sizeof(s->ipi[i]),
+                              TYPE_XLNX_ZYNQMP_IPI);
         g_free(name);
     }
 }