diff --git a/CHANGELOG.md b/CHANGELOG.md
index 82c7d3aa1..2a66091ac 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,8 @@
 # Changelog Fab-manager
 
 - Updated ffi to 1.15.1
+- Updated GitHub issue templates
+- Fix a bug: fablab:fix_invoices task fails to recreate the data if the date is in english
 
 ## v4.7.10 2021 May 25
 
diff --git a/lib/tasks/fablab/fix_invoices.rake b/lib/tasks/fablab/fix_invoices.rake
index 20e2119ab..74747a2da 100644
--- a/lib/tasks/fablab/fix_invoices.rake
+++ b/lib/tasks/fablab/fix_invoices.rake
@@ -98,8 +98,9 @@ namespace :fablab do
       description = ii.description
       # DateTime.parse only works with english dates, so translate the month name
       month_idx = I18n.t('date.month_names').find_index { |month| month && description.include?(month) }
-      description.gsub!(/#{I18n.t('date.month_names')[month_idx]}/, I18n.t('date.month_names', locale: :en)[month_idx])
-
+      unless month_idx.nil?
+        description.gsub!(/#{I18n.t('date.month_names')[month_idx]}/, I18n.t('date.month_names', locale: :en)[month_idx])
+      end
       start = DateTime.parse(description)
       end_time = DateTime.parse(/- (.+)$/.match(description)[1])
       [start, DateTime.new(start.year, start.month, start.day, end_time.hour, end_time.min, end_time.sec, DateTime.current.zone)]