diff --git a/gobject/gtype.c b/gobject/gtype.c
index 72ef32cfc..e2e0c3873 100644
--- a/gobject/gtype.c
+++ b/gobject/gtype.c
@@ -3929,11 +3929,15 @@ type_add_flags_W (TypeNode  *node,
  *     filled in with constant values upon success
  *
  * Queries the type system for information about a specific type.
+ *
  * This function will fill in a user-provided structure to hold
  * type-specific information. If an invalid #GType is passed in, the
  * @type member of the #GTypeQuery is 0. All members filled into the
  * #GTypeQuery structure should be considered constant and have to be
  * left untouched.
+ *
+ * Since GLib 2.78, this function allows queries on dynamic types. Previously
+ * it only supported static types.
  */
 void
 g_type_query (GType       type,
@@ -3943,10 +3947,10 @@ g_type_query (GType       type,
   
   g_return_if_fail (query != NULL);
   
-  /* if node is not static and classed, we won't allow query */
+  /* if node is not classed, we won't allow query */
   query->type = 0;
   node = lookup_type_node_I (type);
-  if (node && node->is_classed && !node->plugin)
+  if (node && node->is_classed)
     {
       /* type is classed and probably even instantiatable */
       G_READ_LOCK (&type_rw_lock);
diff --git a/gobject/tests/dynamictype.c b/gobject/tests/dynamictype.c
index cb33cb690..214211816 100644
--- a/gobject/tests/dynamictype.c
+++ b/gobject/tests/dynamictype.c
@@ -109,8 +109,6 @@ test_dynamic_type (void)
 {
   DynamicObjectClass *class;
 
-  test_module_new (module_register);
-
   /* Not loaded until we call ref for the first time */
   class = g_type_class_peek (DYNAMIC_OBJECT_TYPE);
   g_assert_null (class);
@@ -165,6 +163,27 @@ test_dynamic_type (void)
 #endif
 }
 
+static void
+test_dynamic_type_query (void)
+{
+  DynamicObjectClass *class;
+  GTypeQuery query_result;
+
+  g_test_bug ("https://gitlab.gnome.org/GNOME/glib/-/issues/623");
+
+  class = g_type_class_ref (DYNAMIC_OBJECT_TYPE);
+  g_assert_nonnull (class);
+
+  g_type_query (DYNAMIC_OBJECT_TYPE, &query_result);
+
+  g_assert_cmpuint (query_result.type, !=, 0);
+  g_assert_cmpstr (query_result.type_name, ==, "DynamicObject");
+  g_assert_cmpuint (query_result.class_size, >=, sizeof (DynamicObjectClass));
+  g_assert_cmpuint (query_result.instance_size, >=, sizeof (DynamicObject));
+
+  g_type_class_unref (class);
+}
+
 int
 main (int   argc,
       char *argv[])
@@ -175,7 +194,10 @@ main (int   argc,
 
   g_test_init (&argc, &argv, NULL);
 
+  test_module_new (module_register);
+
   g_test_add_func ("/gobject/dynamic-type", test_dynamic_type);
+  g_test_add_func ("/gobject/dynamic-type/query", test_dynamic_type_query);
 
   return g_test_run ();
 }