diff --git a/target/arm/arm-qmp-cmds.c b/target/arm/arm-qmp-cmds.c
index 2250cd7ddf..0167759730 100644
--- a/target/arm/arm-qmp-cmds.c
+++ b/target/arm/arm-qmp-cmds.c
@@ -104,7 +104,7 @@ CpuModelExpansionInfo *qmp_query_cpu_model_expansion(CpuModelExpansionType type,
                                                      Error **errp)
 {
     CpuModelExpansionInfo *expansion_info;
-    const QDict *qdict_in = NULL;
+    const QDict *qdict_in;
     QDict *qdict_out;
     ObjectClass *oc;
     Object *obj;
@@ -151,27 +151,20 @@ CpuModelExpansionInfo *qmp_query_cpu_model_expansion(CpuModelExpansionType type,
         }
     }
 
-    if (model->props) {
-        qdict_in = qobject_to(QDict, model->props);
-        if (!qdict_in) {
-            error_setg(errp, QERR_INVALID_PARAMETER_TYPE, "props", "dict");
-            return NULL;
-        }
-    }
-
     obj = object_new(object_class_get_name(oc));
 
-    if (qdict_in) {
+    if (model->props) {
         Visitor *visitor;
         Error *err = NULL;
 
         visitor = qobject_input_visitor_new(model->props);
-        if (!visit_start_struct(visitor, NULL, NULL, 0, errp)) {
+        if (!visit_start_struct(visitor, "props", NULL, 0, errp)) {
             visit_free(visitor);
             object_unref(obj);
             return NULL;
         }
 
+        qdict_in = qobject_to(QDict, model->props);
         i = 0;
         while ((name = cpu_model_advertised_features[i++]) != NULL) {
             if (qdict_get(qdict_in, name)) {
diff --git a/target/riscv/riscv-qmp-cmds.c b/target/riscv/riscv-qmp-cmds.c
index c48b9cfa67..69dde0c3e7 100644
--- a/target/riscv/riscv-qmp-cmds.c
+++ b/target/riscv/riscv-qmp-cmds.c
@@ -129,18 +129,19 @@ static void riscv_obj_add_profiles_qdict(Object *obj, QDict *qdict_out)
 }
 
 static void riscv_cpuobj_validate_qdict_in(Object *obj, QObject *props,
-                                           const QDict *qdict_in,
                                            Error **errp)
 {
+    const QDict *qdict_in;
     const QDictEntry *qe;
     Visitor *visitor;
     Error *local_err = NULL;
 
     visitor = qobject_input_visitor_new(props);
-    if (!visit_start_struct(visitor, NULL, NULL, 0, &local_err)) {
+    if (!visit_start_struct(visitor, "props", NULL, 0, &local_err)) {
         goto err;
     }
 
+    qdict_in = qobject_to(QDict, props);
     for (qe = qdict_first(qdict_in); qe; qe = qdict_next(qdict_in, qe)) {
         object_property_find_err(obj, qe->key, &local_err);
         if (local_err) {
@@ -170,7 +171,6 @@ CpuModelExpansionInfo *qmp_query_cpu_model_expansion(CpuModelExpansionType type,
                                                      Error **errp)
 {
     CpuModelExpansionInfo *expansion_info;
-    const QDict *qdict_in = NULL;
     QDict *qdict_out;
     ObjectClass *oc;
     Object *obj;
@@ -188,14 +188,6 @@ CpuModelExpansionInfo *qmp_query_cpu_model_expansion(CpuModelExpansionType type,
         return NULL;
     }
 
-    if (model->props) {
-        qdict_in = qobject_to(QDict, model->props);
-        if (!qdict_in) {
-            error_setg(errp, QERR_INVALID_PARAMETER_TYPE, "props", "dict");
-            return NULL;
-        }
-    }
-
     obj = object_new(object_class_get_name(oc));
 
     riscv_check_if_cpu_available(RISCV_CPU(obj), &local_err);
@@ -205,9 +197,8 @@ CpuModelExpansionInfo *qmp_query_cpu_model_expansion(CpuModelExpansionType type,
         return NULL;
     }
 
-    if (qdict_in) {
-        riscv_cpuobj_validate_qdict_in(obj, model->props, qdict_in,
-                                       &local_err);
+    if (model->props) {
+        riscv_cpuobj_validate_qdict_in(obj, model->props, &local_err);
         if (local_err) {
             error_propagate(errp, local_err);
             object_unref(obj);
diff --git a/target/s390x/cpu_models_sysemu.c b/target/s390x/cpu_models_sysemu.c
index 63981bf36b..ef19724888 100644
--- a/target/s390x/cpu_models_sysemu.c
+++ b/target/s390x/cpu_models_sysemu.c
@@ -101,21 +101,13 @@ static void cpu_model_from_info(S390CPUModel *model, const CpuModelInfo *info,
                                 Error **errp)
 {
     Error *err = NULL;
-    const QDict *qdict = NULL;
+    const QDict *qdict;
     const QDictEntry *e;
     Visitor *visitor;
     ObjectClass *oc;
     S390CPU *cpu;
     Object *obj;
 
-    if (info->props) {
-        qdict = qobject_to(QDict, info->props);
-        if (!qdict) {
-            error_setg(errp, QERR_INVALID_PARAMETER_TYPE, "props", "dict");
-            return;
-        }
-    }
-
     oc = cpu_class_by_name(TYPE_S390_CPU, info->name);
     if (!oc) {
         error_setg(errp, "The CPU definition \'%s\' is unknown.", info->name);
@@ -135,13 +127,14 @@ static void cpu_model_from_info(S390CPUModel *model, const CpuModelInfo *info,
         return;
     }
 
-    if (qdict) {
+    if (info->props) {
         visitor = qobject_input_visitor_new(info->props);
-        if (!visit_start_struct(visitor, NULL, NULL, 0, errp)) {
+        if (!visit_start_struct(visitor, "props", NULL, 0, errp)) {
             visit_free(visitor);
             object_unref(obj);
             return;
         }
+        qdict = qobject_to(QDict, info->props);
         for (e = qdict_first(qdict); e; e = qdict_next(qdict, e)) {
             if (!object_property_set(obj, e->key, visitor, &err)) {
                 break;
diff --git a/tests/qtest/arm-cpu-features.c b/tests/qtest/arm-cpu-features.c
index a8a4c668ad..1daceb2e31 100644
--- a/tests/qtest/arm-cpu-features.c
+++ b/tests/qtest/arm-cpu-features.c
@@ -79,7 +79,7 @@ static const char *resp_get_error(QDict *resp)
     g_assert(_resp);                                                   \
     _error = resp_get_error(_resp);                                    \
     g_assert(_error);                                                  \
-    g_assert(g_str_equal(_error, expected_error));                     \
+    g_assert_cmpstr(_error, ==, expected_error);                       \
     qobject_unref(_resp);                                              \
 })
 
@@ -194,8 +194,8 @@ static void assert_type_full(QTestState *qts)
     g_assert(resp);
     error = resp_get_error(resp);
     g_assert(error);
-    g_assert(g_str_equal(error,
-                         "The requested expansion type is not supported"));
+    g_assert_cmpstr(error, ==,
+                    "The requested expansion type is not supported");
     qobject_unref(resp);
 }
 
@@ -212,8 +212,8 @@ static void assert_bad_props(QTestState *qts, const char *cpu_type)
     g_assert(resp);
     error = resp_get_error(resp);
     g_assert(error);
-    g_assert(g_str_equal(error,
-                         "Invalid parameter type for 'props', expected: dict"));
+    g_assert_cmpstr(error, ==,
+                    "Invalid parameter type for 'props', expected: object");
     qobject_unref(resp);
 }
 
@@ -446,7 +446,7 @@ static void test_query_cpu_model_expansion(const void *data)
     assert_bad_props(qts, "max");
     assert_error(qts, "foo", "The CPU type 'foo' is not a recognized "
                  "ARM CPU type", NULL);
-    assert_error(qts, "max", "Parameter 'not-a-prop' is unexpected",
+    assert_error(qts, "max", "Parameter 'props.not-a-prop' is unexpected",
                  "{ 'not-a-prop': false }");
     assert_error(qts, "host", "The CPU type 'host' requires KVM", NULL);
 
