diff --git a/girepository/girepository.c b/girepository/girepository.c
index e74622e60..0cf6da148 100644
--- a/girepository/girepository.c
+++ b/girepository/girepository.c
@@ -1232,13 +1232,16 @@ gi_repository_get_object_gtype_interfaces (GIRepository      *repository,
 }
 
 static void
-collect_namespaces (gpointer key,
-                    gpointer value,
-                    gpointer data)
+collect_namespaces (GPtrArray  *ordered_typelibs,
+                    char      **names,
+                    size_t     *inout_i)
 {
-  GList **list = data;
-
-  *list = g_list_append (*list, key);
+  for (guint j = 0; j < ordered_typelibs->len; j++)
+    {
+      GITypelib *typelib = g_ptr_array_index (ordered_typelibs, j);
+      const char *namespace = gi_typelib_get_namespace (typelib);
+      names[(*inout_i)++] = g_strdup (namespace);
+    }
 }
 
 /**
@@ -1260,20 +1263,18 @@ char **
 gi_repository_get_loaded_namespaces (GIRepository *repository,
                                      size_t       *n_namespaces_out)
 {
-  GList *l, *list = NULL;
   char **names;
   size_t i;
+  size_t n_typelibs;
 
   g_return_val_if_fail (GI_IS_REPOSITORY (repository), NULL);
 
-  g_hash_table_foreach (repository->typelibs, collect_namespaces, &list);
-  g_hash_table_foreach (repository->lazy_typelibs, collect_namespaces, &list);
-
-  names = g_malloc0 (sizeof (char *) * (g_list_length (list) + 1));
+  n_typelibs = repository->ordered_typelibs->len + repository->ordered_lazy_typelibs->len;
+  names = g_malloc0 (sizeof (char *) * (n_typelibs + 1));
   i = 0;
-  for (l = list; l; l = l->next)
-    names[i++] = g_strdup (l->data);
-  g_list_free (list);
+
+  collect_namespaces (repository->ordered_typelibs, names, &i);
+  collect_namespaces (repository->ordered_lazy_typelibs, names, &i);
 
   if (n_namespaces_out != NULL)
     *n_namespaces_out = i;
diff --git a/girepository/tests/repository.c b/girepository/tests/repository.c
index 55cbcb0ce..c79b0df9a 100644
--- a/girepository/tests/repository.c
+++ b/girepository/tests/repository.c
@@ -863,6 +863,35 @@ test_repository_find_by_gtype (RepositoryFixture *fx,
   }
 }
 
+static void
+test_repository_loaded_namespaces (RepositoryFixture *fx,
+                                   const void        *unused)
+{
+  char **namespaces;
+  size_t n_namespaces;
+
+  /* These should be in alphabetical order */
+#if defined(G_OS_UNIX)
+  const char *expected_namespaces[] = { "GLib", "GModule", "GObject", "Gio", "GioUnix", NULL };
+#elif defined(G_OS_WIN32)
+  const char *expected_namespaces[] = { "GLib", "GModule", "GObject", "Gio", "GioWin32", NULL };
+#else
+  const char *expected_namespaces[] = { "GLib", "GModule", "GObject", "Gio", NULL };
+#endif
+
+  g_test_summary ("Test listing loaded namespaces");
+
+  namespaces = gi_repository_get_loaded_namespaces (fx->repository, &n_namespaces);
+  g_assert_cmpstrv (namespaces, expected_namespaces);
+  g_assert_cmpuint (n_namespaces, ==, g_strv_length ((char **) expected_namespaces));
+  g_strfreev (namespaces);
+
+  /* Test again but without passing `n_namespaces`. */
+  namespaces = gi_repository_get_loaded_namespaces (fx->repository, NULL);
+  g_assert_cmpstrv (namespaces, expected_namespaces);
+  g_strfreev (namespaces);
+}
+
 int
 main (int   argc,
       char *argv[])
@@ -891,6 +920,7 @@ main (int   argc,
   ADD_REPOSITORY_TEST ("/repository/vfunc-info-with-invoker-on-interface", test_repository_vfunc_info_with_invoker_on_interface, &typelib_load_spec_gio);
   ADD_REPOSITORY_TEST ("/repository/vfunc-info-with-invoker-on-object", test_repository_vfunc_info_with_invoker_on_object, &typelib_load_spec_gio);
   ADD_REPOSITORY_TEST ("/repository/find-by-gtype", test_repository_find_by_gtype, &typelib_load_spec_gio_platform);
+  ADD_REPOSITORY_TEST ("/repository/loaded-namespaces", test_repository_loaded_namespaces, &typelib_load_spec_gio_platform);
 
   return g_test_run ();
 }