diff --git a/include/qapi/qmp-output-visitor.h b/include/qapi/qmp-output-visitor.h
index 2266770..5093f0d 100644
--- a/include/qapi/qmp-output-visitor.h
+++ b/include/qapi/qmp-output-visitor.h
@@ -21,6 +21,7 @@ typedef struct QmpOutputVisitor QmpOutputVisitor;

 QmpOutputVisitor *qmp_output_visitor_new(void);
 void qmp_output_visitor_cleanup(QmpOutputVisitor *v);
+void qmp_output_visitor_reset(QmpOutputVisitor *v);

 QObject *qmp_output_get_qobject(QmpOutputVisitor *v);
 Visitor *qmp_output_get_visitor(QmpOutputVisitor *v);
diff --git a/qapi/qmp-output-visitor.c b/qapi/qmp-output-visitor.c
index 5681ad3..7c48dfb 100644
--- a/qapi/qmp-output-visitor.c
+++ b/qapi/qmp-output-visitor.c
@@ -82,9 +82,8 @@ static void qmp_output_add_obj(QmpOutputVisitor *qov, const char *name,
     QObject *cur = e ? e->value : NULL;

     if (!cur) {
-        /* FIXME we should require the user to reset the visitor, rather
-         * than throwing away the previous root */
-        qobject_decref(qov->root);
+        /* Don't allow reuse of visitor on more than one root */
+        assert(!qov->root);
         qov->root = value;
     } else {
         switch (qobject_type(cur)) {
@@ -93,6 +92,9 @@ static void qmp_output_add_obj(QmpOutputVisitor *qov, const char *name,
             qdict_put_obj(qobject_to_qdict(cur), name, value);
             break;
         case QTYPE_QLIST:
+            /* FIXME: assertion needs adjustment if we fix visit-core
+             * to pass "name.0" style name during lists.  */
+            assert(!name);
             qlist_append_obj(qobject_to_qlist(cur), value);
             break;
         default:
@@ -114,7 +116,8 @@ static void qmp_output_start_struct(Visitor *v, const char *name, void **obj,
 static void qmp_output_end_struct(Visitor *v, Error **errp)
 {
     QmpOutputVisitor *qov = to_qov(v);
-    qmp_output_pop(qov);
+    QObject *value = qmp_output_pop(qov);
+    assert(qobject_type(value) == QTYPE_QDICT);
 }

 static void qmp_output_start_list(Visitor *v, const char *name, Error **errp)
@@ -145,7 +148,8 @@ static GenericList *qmp_output_next_list(Visitor *v, GenericList **listp,
 static void qmp_output_end_list(Visitor *v)
 {
     QmpOutputVisitor *qov = to_qov(v);
-    qmp_output_pop(qov);
+    QObject *value = qmp_output_pop(qov);
+    assert(qobject_type(value) == QTYPE_QLIST);
 }

 static void qmp_output_type_int64(Visitor *v, const char *name, int64_t *obj,
@@ -202,18 +206,15 @@ static void qmp_output_type_null(Visitor *v, const char *name, Error **errp)
     qmp_output_add_obj(qov, name, qnull());
 }

-/* Finish building, and return the root object. Will not be NULL. */
+/* Finish building, and return the root object. Will not be NULL.
+ * Caller must use qobject_decref() on the result.  */
 QObject *qmp_output_get_qobject(QmpOutputVisitor *qov)
 {
-    /* FIXME: we should require that a visit occurred, and that it is
-     * complete (no starts without a matching end) */
-    QObject *obj = qov->root;
-    if (obj) {
-        qobject_incref(obj);
-    } else {
-        obj = qnull();
-    }
-    return obj;
+    /* A visit must have occurred, with each start paired with end.  */
+    assert(qov->root && !QTAILQ_FIRST(&qov->stack));
+
+    qobject_incref(qov->root);
+    return qov->root;
 }

 Visitor *qmp_output_get_visitor(QmpOutputVisitor *v)
@@ -221,7 +222,7 @@ Visitor *qmp_output_get_visitor(QmpOutputVisitor *v)
     return &v->visitor;
 }

-void qmp_output_visitor_cleanup(QmpOutputVisitor *v)
+void qmp_output_visitor_reset(QmpOutputVisitor *v)
 {
     QStackEntry *e, *tmp;

@@ -231,6 +232,12 @@ void qmp_output_visitor_cleanup(QmpOutputVisitor *v)
     }

     qobject_decref(v->root);
+    v->root = NULL;
+}
+
+void qmp_output_visitor_cleanup(QmpOutputVisitor *v)
+{
+    qmp_output_visitor_reset(v);
     g_free(v);
 }

diff --git a/tests/test-qmp-output-visitor.c b/tests/test-qmp-output-visitor.c
index 4f7692b..e9ebce7 100644
--- a/tests/test-qmp-output-visitor.c
+++ b/tests/test-qmp-output-visitor.c
@@ -138,6 +138,7 @@ static void test_visitor_out_enum(TestOutputVisitorData *data,
         g_assert_cmpstr(qstring_get_str(qobject_to_qstring(obj)), ==,
                         EnumOne_lookup[i]);
         qobject_decref(obj);
+        qmp_output_visitor_reset(data->qov);
     }
 }

@@ -152,6 +153,7 @@ static void test_visitor_out_enum_errors(TestOutputVisitorData *data,
         visit_type_EnumOne(data->ov, "unused", &bad_values[i], &err);
         g_assert(err);
         error_free(err);
+        qmp_output_visitor_reset(data->qov);
     }
 }

@@ -261,6 +263,7 @@ static void test_visitor_out_struct_errors(TestOutputVisitorData *data,
         visit_type_UserDefOne(data->ov, "unused", &pu, &err);
         g_assert(err);
         error_free(err);
+        qmp_output_visitor_reset(data->qov);
     }
 }

@@ -365,6 +368,7 @@ static void test_visitor_out_any(TestOutputVisitorData *data,
     qobject_decref(obj);
     qobject_decref(qobj);

+    qmp_output_visitor_reset(data->qov);
     qdict = qdict_new();
     qdict_put(qdict, "integer", qint_from_int(-42));
     qdict_put(qdict, "boolean", qbool_from_bool(true));
@@ -441,6 +445,7 @@ static void test_visitor_out_alternate(TestOutputVisitorData *data,
     qapi_free_UserDefAlternate(tmp);
     qobject_decref(arg);

+    qmp_output_visitor_reset(data->qov);
     tmp = g_new0(UserDefAlternate, 1);
     tmp->type = QTYPE_QSTRING;
     tmp->u.s = g_strdup("hello");
@@ -454,6 +459,7 @@ static void test_visitor_out_alternate(TestOutputVisitorData *data,
     qapi_free_UserDefAlternate(tmp);
     qobject_decref(arg);

+    qmp_output_visitor_reset(data->qov);
     tmp = g_new0(UserDefAlternate, 1);
     tmp->type = QTYPE_QDICT;
     tmp->u.udfu.integer = 1;
