Can't localize terms with i18n_taxonomy_localize_terms

I'm trying to localize terms of a localizable vocabulary. However, i18n_taxonomy_localize_terms doesn't seem to localize them because i18n_taxonomy_vocabulary_mode returns a string whereas I18N_MODE_LOCALIZE is an integer.

They are equal (value is 1), but not identical (string versus integer), so it seems like the following comparison will always return false:

if (i18n_taxonomy_vocabulary_mode($term->vid) === I18N_MODE_LOCALIZE) {

To reproduce this issue, run following code (replace $vid with the vid of your localizable vocabulary):

  $vid = 5;
  
  $taxonomy_mode = i18n_taxonomy_vocabulary_mode($vid);
  $localize_mode = I18N_MODE_LOCALIZE;
  
  if(is_string($taxonomy_mode)) dpm('taxonomy mode = '.$taxonomy_mode. ' ('.gettype($taxonomy_mode).')');
  if(is_int($localize_mode)) dpm('localizable mode = '.$localize_mode.' ('.gettype($localize_mode).')');