diff --git a/gtk/gtkaboutdialog.c b/gtk/gtkaboutdialog.c
index 1c33631696..94aeabefb6 100644
--- a/gtk/gtkaboutdialog.c
+++ b/gtk/gtkaboutdialog.c
@@ -135,6 +135,9 @@ static const LicenseInfo gtk_license_info [] = {
   { N_("Apache License, Version 2.0"), "https://opensource.org/licenses/Apache-2.0" },
   { N_("Mozilla Public License 2.0"), "https://opensource.org/licenses/MPL-2.0" }
 };
+/* Keep this static assertion updated with the last element of the
+ * enumeration, and make sure it matches the last element of the array */
+G_STATIC_ASSERT (G_N_ELEMENTS (gtk_license_info) - 1 == GTK_LICENSE_MPL_2_0);
 
 typedef struct
 {
@@ -2345,7 +2348,7 @@ gtk_about_dialog_set_license_type (GtkAboutDialog *about,
 {
   g_return_if_fail (GTK_IS_ABOUT_DIALOG (about));
   g_return_if_fail (license_type >= GTK_LICENSE_UNKNOWN &&
-                    license_type <= GTK_LICENSE_AGPL_3_0_ONLY);
+                    license_type < G_N_ELEMENTS (gtk_license_info));
 
   if (about->license_type != license_type)
     {