diff --git a/src/gtk/assertdlg_gtk.cpp b/src/gtk/assertdlg_gtk.cpp
index 34c193bdde..23fa8a7286 100644
--- a/src/gtk/assertdlg_gtk.cpp
+++ b/src/gtk/assertdlg_gtk.cpp
@@ -841,12 +841,12 @@ gchar *gtk_assert_dialog_get_backtrace (GtkAssertDialog *dlg)
 
     g_return_val_if_fail (GTK_IS_ASSERT_DIALOG (dlg), NULL);
     model = gtk_tree_view_get_model (GTK_TREE_VIEW(dlg->treeview));
-    string = g_string_new("");
 
     /* iterate over the list */
     if (!gtk_tree_model_get_iter_first (model, &iter))
         return NULL;
 
+    string = g_string_new("");
     do
     {
         /* append this stack frame's info to the string */
@@ -879,13 +879,13 @@ gchar *gtk_assert_dialog_get_backtrace (GtkAssertDialog *dlg)
 
 void gtk_assert_dialog_set_message(GtkAssertDialog *dlg, const gchar *msg)
 {
+    g_return_if_fail (GTK_IS_ASSERT_DIALOG (dlg));
     /* prepend and append the <b> tag
        NOTE: g_markup_printf_escaped() is not used because it's available
              only for glib >= 2.4 */
     gchar *escaped_msg = g_markup_escape_text (msg, -1);
     gchar *decorated_msg = g_strdup_printf ("<b>%s</b>", escaped_msg);
 
-    g_return_if_fail (GTK_IS_ASSERT_DIALOG (dlg));
     gtk_label_set_markup (GTK_LABEL(dlg->message), decorated_msg);
 
     g_free (decorated_msg);