diff --git a/libmalcontent-ui/gs-content-rating.c b/libmalcontent-ui/gs-content-rating.c
index e7b0eea..bf18894 100644
--- a/libmalcontent-ui/gs-content-rating.c
+++ b/libmalcontent-ui/gs-content-rating.c
@@ -509,9 +509,16 @@ static guint content_rating_ages[GS_CONTENT_RATING_SYSTEM_LAST][7] = {
 };
 
 const guint *
-gs_utils_content_rating_get_ages (GsContentRatingSystem system)
+gs_utils_content_rating_get_ages (GsContentRatingSystem system, gsize *length_out)
 {
-	g_assert (system < GS_CONTENT_RATING_SYSTEM_LAST);
+	g_return_val_if_fail ((int) system < GS_CONTENT_RATING_SYSTEM_LAST, NULL);
+	g_return_val_if_fail (length_out != NULL, NULL);
+
+	/* IARC is the fallback for everything */
+	if (system == GS_CONTENT_RATING_SYSTEM_UNKNOWN)
+		system = GS_CONTENT_RATING_SYSTEM_IARC;
+
+	*length_out = g_strv_length ((gchar **) content_rating_strings[system]);
 	return content_rating_ages[system];
 }
 
diff --git a/libmalcontent-ui/gs-content-rating.h b/libmalcontent-ui/gs-content-rating.h
index 3b79460..59f5415 100644
--- a/libmalcontent-ui/gs-content-rating.h
+++ b/libmalcontent-ui/gs-content-rating.h
@@ -52,7 +52,7 @@ gchar *gs_utils_content_rating_age_to_str (GsContentRatingSystem system,
 GsContentRatingSystem gs_utils_content_rating_system_from_locale (const gchar *locale);
 const gchar *gs_content_rating_system_to_str (GsContentRatingSystem system);
 gchar **gs_utils_content_rating_get_values (GsContentRatingSystem system);
-const guint *gs_utils_content_rating_get_ages (GsContentRatingSystem system);
+const guint *gs_utils_content_rating_get_ages (GsContentRatingSystem system, gsize *length_out);
 guint as_content_rating_id_value_to_csm_age (const gchar *id, MctAppFilterOarsValue value);
 MctAppFilterOarsValue as_content_rating_id_csm_age_to_value (const gchar *id, guint age);
 
diff --git a/libmalcontent-ui/user-controls.c b/libmalcontent-ui/user-controls.c
index e1baf7b..84d0d13 100644
--- a/libmalcontent-ui/user-controls.c
+++ b/libmalcontent-ui/user-controls.c
@@ -319,7 +319,7 @@ update_categories_from_language (MctUserControls *self)
   g_auto(GStrv) entries = NULL;
   const gchar *rating_system_str;
   const guint *ages;
-  gsize i;
+  gsize i, n_ages;
   g_autofree gchar *disabled_action = NULL;
 
   rating_system = get_content_rating_system (self);
@@ -328,7 +328,7 @@ update_categories_from_language (MctUserControls *self)
   g_debug ("Using rating system %s", rating_system_str);
 
   entries = gs_utils_content_rating_get_values (rating_system);
-  ages = gs_utils_content_rating_get_ages (rating_system);
+  ages = gs_utils_content_rating_get_ages (rating_system, &n_ages);
 
   /* Fill in the age menu */
   g_menu_remove_all (self->age_menu);
@@ -346,6 +346,8 @@ update_categories_from_language (MctUserControls *self)
 
       g_menu_append (self->age_menu, entries[i], action);
     }
+
+  g_assert (i == n_ages);
 }
 
 /* Returns a human-readable but untranslated string, not suitable
@@ -684,13 +686,14 @@ on_set_age_action_activated (GSimpleAction *action,
   const guint *ages;
   guint age;
   guint i;
+  gsize n_ages;
 
   self = MCT_USER_CONTROLS (user_data);
   age = g_variant_get_uint32 (param);
 
   rating_system = get_content_rating_system (self);
   entries = gs_utils_content_rating_get_values (rating_system);
-  ages = gs_utils_content_rating_get_ages (rating_system);
+  ages = gs_utils_content_rating_get_ages (rating_system, &n_ages);
 
   /* Update the button */
   if (age == oars_disabled_age)