diff --git a/lib/tasks/2018_09_27_fill_missing_en_instruction_at.rake b/lib/tasks/2018_09_27_fill_missing_en_instruction_at.rake
new file mode 100644
index 000000000..e100e11ef
--- /dev/null
+++ b/lib/tasks/2018_09_27_fill_missing_en_instruction_at.rake
@@ -0,0 +1,9 @@
+namespace :'2018_09_27_fill_missing_en_instruction_at' do
+  task run: :environment do
+    dossiers_with_missing_instruction_at = Dossier
+      .where.not(processed_at: nil)
+      .where(en_instruction_at: nil)
+
+    dossiers_with_missing_instruction_at.each { |d| d.update(en_instruction_at: d.processed_at) }
+  end
+end