diff --git a/hw/isa/isa-superio.c b/hw/isa/isa-superio.c
index 7dbfc374da..d85f22db1a 100644
--- a/hw/isa/isa-superio.c
+++ b/hw/isa/isa-superio.c
@@ -185,6 +185,7 @@ static const TypeInfo isa_superio_type_info = {
     .abstract = true,
     .class_size = sizeof(ISASuperIOClass),
     .class_init = isa_superio_class_init,
+    .instance_size = sizeof(ISASuperIODevice),
 };
 
 /* SMS FDC37M817 Super I/O */
@@ -201,7 +202,6 @@ static void fdc37m81x_class_init(ObjectClass *klass, void *data)
 static const TypeInfo fdc37m81x_type_info = {
     .name          = TYPE_FDC37M81X_SUPERIO,
     .parent        = TYPE_ISA_SUPERIO,
-    .instance_size = sizeof(ISASuperIODevice),
     .class_init    = fdc37m81x_class_init,
 };
 
diff --git a/hw/isa/smc37c669-superio.c b/hw/isa/smc37c669-superio.c
index 18287741cb..9e59dc1603 100644
--- a/hw/isa/smc37c669-superio.c
+++ b/hw/isa/smc37c669-superio.c
@@ -103,7 +103,6 @@ static void smc37c669_class_init(ObjectClass *klass, void *data)
 static const TypeInfo smc37c669_type_info = {
     .name          = TYPE_SMC37C669_SUPERIO,
     .parent        = TYPE_ISA_SUPERIO,
-    .instance_size = sizeof(ISASuperIODevice),
     .class_size    = sizeof(ISASuperIOClass),
     .class_init    = smc37c669_class_init,
 };