diff --git a/tests/qapi-schema/qapi-schema-test.json b/tests/qapi-schema/qapi-schema-test.json
index 8405021..c7e6be8 100644
--- a/tests/qapi-schema/qapi-schema-test.json
+++ b/tests/qapi-schema/qapi-schema-test.json
@@ -7,8 +7,12 @@
   'data': { 'enum1': 'EnumOne', '*enum2': 'EnumOne', 'enum3': 'EnumOne', '*enum4': 'EnumOne' } }
 
 # for testing nested structs
+{ 'type': 'UserDefZero',
+  'data': { 'integer': 'int' } }
+
 { 'type': 'UserDefOne',
-  'data': { 'integer': 'int', 'string': 'str', '*enum1': 'EnumOne' } }
+  'base': 'UserDefZero',
+  'data': { 'string': 'str', '*enum1': 'EnumOne' } }
 
 { 'type': 'UserDefTwo',
   'data': { 'string': 'str',
diff --git a/tests/qapi-schema/qapi-schema-test.out b/tests/qapi-schema/qapi-schema-test.out
index ac98f32..89e213a 100644
--- a/tests/qapi-schema/qapi-schema-test.out
+++ b/tests/qapi-schema/qapi-schema-test.out
@@ -1,6 +1,7 @@
 [OrderedDict([('enum', 'EnumOne'), ('data', ['value1', 'value2', 'value3'])]),
  OrderedDict([('type', 'NestedEnumsOne'), ('data', OrderedDict([('enum1', 'EnumOne'), ('*enum2', 'EnumOne'), ('enum3', 'EnumOne'), ('*enum4', 'EnumOne')]))]),
- OrderedDict([('type', 'UserDefOne'), ('data', OrderedDict([('integer', 'int'), ('string', 'str'), ('*enum1', 'EnumOne')]))]),
+ OrderedDict([('type', 'UserDefZero'), ('data', OrderedDict([('integer', 'int')]))]),
+ OrderedDict([('type', 'UserDefOne'), ('base', 'UserDefZero'), ('data', OrderedDict([('string', 'str'), ('*enum1', 'EnumOne')]))]),
  OrderedDict([('type', 'UserDefTwo'), ('data', OrderedDict([('string', 'str'), ('dict', OrderedDict([('string', 'str'), ('dict', OrderedDict([('userdef', 'UserDefOne'), ('string', 'str')])), ('*dict2', OrderedDict([('userdef', 'UserDefOne'), ('string', 'str')]))]))]))]),
  OrderedDict([('type', 'UserDefNested'), ('data', OrderedDict([('string0', 'str'), ('dict1', OrderedDict([('string1', 'str'), ('dict2', OrderedDict([('userdef1', 'UserDefOne'), ('string2', 'str')])), ('*dict3', OrderedDict([('userdef2', 'UserDefOne'), ('string3', 'str')]))]))]))]),
  OrderedDict([('type', 'UserDefA'), ('data', OrderedDict([('boolean', 'bool')]))]),
@@ -18,7 +19,8 @@
  'UserDefAnonUnionKind',
  'UserDefNativeListUnionKind']
 [OrderedDict([('type', 'NestedEnumsOne'), ('data', OrderedDict([('enum1', 'EnumOne'), ('*enum2', 'EnumOne'), ('enum3', 'EnumOne'), ('*enum4', 'EnumOne')]))]),
- OrderedDict([('type', 'UserDefOne'), ('data', OrderedDict([('integer', 'int'), ('string', 'str'), ('*enum1', 'EnumOne')]))]),
+ OrderedDict([('type', 'UserDefZero'), ('data', OrderedDict([('integer', 'int')]))]),
+ OrderedDict([('type', 'UserDefOne'), ('base', 'UserDefZero'), ('data', OrderedDict([('string', 'str'), ('*enum1', 'EnumOne')]))]),
  OrderedDict([('type', 'UserDefTwo'), ('data', OrderedDict([('string', 'str'), ('dict', OrderedDict([('string', 'str'), ('dict', OrderedDict([('userdef', 'UserDefOne'), ('string', 'str')])), ('*dict2', OrderedDict([('userdef', 'UserDefOne'), ('string', 'str')]))]))]))]),
  OrderedDict([('type', 'UserDefNested'), ('data', OrderedDict([('string0', 'str'), ('dict1', OrderedDict([('string1', 'str'), ('dict2', OrderedDict([('userdef1', 'UserDefOne'), ('string2', 'str')])), ('*dict3', OrderedDict([('userdef2', 'UserDefOne'), ('string3', 'str')]))]))]))]),
  OrderedDict([('type', 'UserDefA'), ('data', OrderedDict([('boolean', 'bool')]))]),
diff --git a/tests/test-qmp-commands.c b/tests/test-qmp-commands.c
index 4586cee..8e62c2d 100644
--- a/tests/test-qmp-commands.c
+++ b/tests/test-qmp-commands.c
@@ -25,9 +25,11 @@ UserDefTwo *qmp_user_def_cmd2(UserDefOne *ud1a,
     UserDefOne *ud1d = g_malloc0(sizeof(UserDefOne));
 
     ud1c->string = strdup(ud1a->string);
-    ud1c->integer = ud1a->integer;
+    ud1c->base = g_new0(UserDefZero, 1);
+    ud1c->base->integer = ud1a->base->integer;
     ud1d->string = strdup(has_udb1 ? ud1b->string : "blah0");
-    ud1d->integer = has_udb1 ? ud1b->integer : 0;
+    ud1d->base = g_new0(UserDefZero, 1);
+    ud1d->base->integer = has_udb1 ? ud1b->base->integer : 0;
 
     ret = g_malloc0(sizeof(UserDefTwo));
     ret->string = strdup("blah1");
@@ -151,17 +153,20 @@ static void test_dealloc_types(void)
     UserDefOneList *ud1list;
 
     ud1test = g_malloc0(sizeof(UserDefOne));
-    ud1test->integer = 42;
+    ud1test->base = g_new0(UserDefZero, 1);
+    ud1test->base->integer = 42;
     ud1test->string = g_strdup("hi there 42");
 
     qapi_free_UserDefOne(ud1test);
 
     ud1a = g_malloc0(sizeof(UserDefOne));
-    ud1a->integer = 43;
+    ud1a->base = g_new0(UserDefZero, 1);
+    ud1a->base->integer = 43;
     ud1a->string = g_strdup("hi there 43");
 
     ud1b = g_malloc0(sizeof(UserDefOne));
-    ud1b->integer = 44;
+    ud1b->base = g_new0(UserDefZero, 1);
+    ud1b->base->integer = 44;
     ud1b->string = g_strdup("hi there 44");
 
     ud1list = g_malloc0(sizeof(UserDefOneList));
diff --git a/tests/test-qmp-input-visitor.c b/tests/test-qmp-input-visitor.c
index eadb6e9..9c7bf38 100644
--- a/tests/test-qmp-input-visitor.c
+++ b/tests/test-qmp-input-visitor.c
@@ -252,7 +252,7 @@ static void test_visitor_in_struct_nested(TestInputVisitorData *data,
 
     check_and_free_str(udp->string0, "string0");
     check_and_free_str(udp->dict1.string1, "string1");
-    g_assert_cmpint(udp->dict1.dict2.userdef1->integer, ==, 42);
+    g_assert_cmpint(udp->dict1.dict2.userdef1->base->integer, ==, 42);
     check_and_free_str(udp->dict1.dict2.userdef1->string, "string");
     check_and_free_str(udp->dict1.dict2.string2, "string2");
     g_assert(udp->dict1.has_dict3 == false);
@@ -280,7 +280,7 @@ static void test_visitor_in_list(TestInputVisitorData *data,
 
         snprintf(string, sizeof(string), "string%d", i);
         g_assert_cmpstr(item->value->string, ==, string);
-        g_assert_cmpint(item->value->integer, ==, 42 + i);
+        g_assert_cmpint(item->value->base->integer, ==, 42 + i);
     }
 
     qapi_free_UserDefOneList(head);
diff --git a/tests/test-qmp-output-visitor.c b/tests/test-qmp-output-visitor.c
index ae4e68c..6b29849 100644
--- a/tests/test-qmp-output-visitor.c
+++ b/tests/test-qmp-output-visitor.c
@@ -231,13 +231,15 @@ static void test_visitor_out_struct_nested(TestOutputVisitorData *data,
     ud2->dict1.string1 = g_strdup(strings[1]);
     ud2->dict1.dict2.userdef1 = g_malloc0(sizeof(UserDefOne));
     ud2->dict1.dict2.userdef1->string = g_strdup(string);
-    ud2->dict1.dict2.userdef1->integer = value;
+    ud2->dict1.dict2.userdef1->base = g_new0(UserDefZero, 1);
+    ud2->dict1.dict2.userdef1->base->integer = value;
     ud2->dict1.dict2.string2 = g_strdup(strings[2]);
 
     ud2->dict1.has_dict3 = true;
     ud2->dict1.dict3.userdef2 = g_malloc0(sizeof(UserDefOne));
     ud2->dict1.dict3.userdef2->string = g_strdup(string);
-    ud2->dict1.dict3.userdef2->integer = value;
+    ud2->dict1.dict3.userdef2->base = g_new0(UserDefZero, 1);
+    ud2->dict1.dict3.userdef2->base->integer = value;
     ud2->dict1.dict3.string3 = g_strdup(strings[3]);
 
     visit_type_UserDefNested(data->ov, &ud2, "unused", &errp);
@@ -279,7 +281,8 @@ static void test_visitor_out_struct_errors(TestOutputVisitorData *data,
                                            const void *unused)
 {
     EnumOne bad_values[] = { ENUM_ONE_MAX, -1 };
-    UserDefOne u = { 0 }, *pu = &u;
+    UserDefZero b;
+    UserDefOne u = { .base = &b }, *pu = &u;
     Error *errp;
     int i;
 
@@ -391,7 +394,8 @@ static void test_visitor_out_list_qapi_free(TestOutputVisitorData *data,
         p->value->dict1.string1 = g_strdup(string);
         p->value->dict1.dict2.userdef1 = g_malloc0(sizeof(UserDefOne));
         p->value->dict1.dict2.userdef1->string = g_strdup(string);
-        p->value->dict1.dict2.userdef1->integer = 42;
+        p->value->dict1.dict2.userdef1->base = g_new0(UserDefZero, 1);
+        p->value->dict1.dict2.userdef1->base->integer = 42;
         p->value->dict1.dict2.string2 = g_strdup(string);
         p->value->dict1.has_dict3 = false;
 
diff --git a/tests/test-visitor-serialization.c b/tests/test-visitor-serialization.c
index 6bff950..8166cf1 100644
--- a/tests/test-visitor-serialization.c
+++ b/tests/test-visitor-serialization.c
@@ -239,12 +239,14 @@ static UserDefNested *nested_struct_create(void)
     udnp->string0 = strdup("test_string0");
     udnp->dict1.string1 = strdup("test_string1");
     udnp->dict1.dict2.userdef1 = g_malloc0(sizeof(UserDefOne));
-    udnp->dict1.dict2.userdef1->integer = 42;
+    udnp->dict1.dict2.userdef1->base = g_new0(UserDefZero, 1);
+    udnp->dict1.dict2.userdef1->base->integer = 42;
     udnp->dict1.dict2.userdef1->string = strdup("test_string");
     udnp->dict1.dict2.string2 = strdup("test_string2");
     udnp->dict1.has_dict3 = true;
     udnp->dict1.dict3.userdef2 = g_malloc0(sizeof(UserDefOne));
-    udnp->dict1.dict3.userdef2->integer = 43;
+    udnp->dict1.dict3.userdef2->base = g_new0(UserDefZero, 1);
+    udnp->dict1.dict3.userdef2->base->integer = 43;
     udnp->dict1.dict3.userdef2->string = strdup("test_string");
     udnp->dict1.dict3.string3 = strdup("test_string3");
     return udnp;
@@ -256,14 +258,14 @@ static void nested_struct_compare(UserDefNested *udnp1, UserDefNested *udnp2)
     g_assert(udnp2);
     g_assert_cmpstr(udnp1->string0, ==, udnp2->string0);
     g_assert_cmpstr(udnp1->dict1.string1, ==, udnp2->dict1.string1);
-    g_assert_cmpint(udnp1->dict1.dict2.userdef1->integer, ==,
-                    udnp2->dict1.dict2.userdef1->integer);
+    g_assert_cmpint(udnp1->dict1.dict2.userdef1->base->integer, ==,
+                    udnp2->dict1.dict2.userdef1->base->integer);
     g_assert_cmpstr(udnp1->dict1.dict2.userdef1->string, ==,
                     udnp2->dict1.dict2.userdef1->string);
     g_assert_cmpstr(udnp1->dict1.dict2.string2, ==, udnp2->dict1.dict2.string2);
     g_assert(udnp1->dict1.has_dict3 == udnp2->dict1.has_dict3);
-    g_assert_cmpint(udnp1->dict1.dict3.userdef2->integer, ==,
-                    udnp2->dict1.dict3.userdef2->integer);
+    g_assert_cmpint(udnp1->dict1.dict3.userdef2->base->integer, ==,
+                    udnp2->dict1.dict3.userdef2->base->integer);
     g_assert_cmpstr(udnp1->dict1.dict3.userdef2->string, ==,
                     udnp2->dict1.dict3.userdef2->string);
     g_assert_cmpstr(udnp1->dict1.dict3.string3, ==, udnp2->dict1.dict3.string3);
