diff --git a/app/controllers/instructeurs/avis_controller.rb b/app/controllers/instructeurs/avis_controller.rb
index 933aa64a7..ba8997448 100644
--- a/app/controllers/instructeurs/avis_controller.rb
+++ b/app/controllers/instructeurs/avis_controller.rb
@@ -60,6 +60,7 @@ module Instructeurs
       @commentaire = CommentaireService.build(current_instructeur, avis.dossier, commentaire_params)
 
       if @commentaire.save
+        @commentaire.dossier.update!(last_commentaire_updated_at: Time.zone.now)
         flash.notice = "Message envoyé"
         redirect_to messagerie_instructeur_avis_path(avis.procedure, avis)
       else
diff --git a/app/controllers/instructeurs/dossiers_controller.rb b/app/controllers/instructeurs/dossiers_controller.rb
index 85b21678d..4ad0cbe88 100644
--- a/app/controllers/instructeurs/dossiers_controller.rb
+++ b/app/controllers/instructeurs/dossiers_controller.rb
@@ -169,6 +169,7 @@ module Instructeurs
       @commentaire = CommentaireService.build(current_instructeur, dossier, commentaire_params)
 
       if @commentaire.save
+        @commentaire.dossier.update!(last_commentaire_updated_at: Time.zone.now)
         current_instructeur.follow(dossier)
         flash.notice = "Message envoyé"
         redirect_to messagerie_instructeur_dossier_path(procedure, dossier)
diff --git a/app/controllers/users/dossiers_controller.rb b/app/controllers/users/dossiers_controller.rb
index 93a62ad67..0fe661950 100644
--- a/app/controllers/users/dossiers_controller.rb
+++ b/app/controllers/users/dossiers_controller.rb
@@ -198,6 +198,7 @@ module Users
       @commentaire = CommentaireService.build(current_user, dossier, commentaire_params)
 
       if @commentaire.save
+        @commentaire.dossier.update!(last_commentaire_updated_at: Time.zone.now)
         dossier.followers_instructeurs
           .with_instant_email_message_notifications
           .each do |instructeur|
diff --git a/spec/controllers/instructeurs/avis_controller_spec.rb b/spec/controllers/instructeurs/avis_controller_spec.rb
index 1d805df7d..b220573cc 100644
--- a/spec/controllers/instructeurs/avis_controller_spec.rb
+++ b/spec/controllers/instructeurs/avis_controller_spec.rb
@@ -117,18 +117,23 @@ describe Instructeurs::AvisController, type: :controller do
     describe '#create_commentaire' do
       let(:file) { nil }
       let(:scan_result) { true }
+      let(:now) { Time.zone.parse("14/07/1789") }
 
       subject { post :create_commentaire, params: { id: avis_without_answer.id, procedure_id: procedure.id, commentaire: { body: 'commentaire body', piece_jointe: file } } }
 
       before do
         allow(ClamavService).to receive(:safe_file?).and_return(scan_result)
+        Timecop.freeze(now)
       end
 
+      after { Timecop.return }
+
       it do
         subject
 
         expect(response).to redirect_to(messagerie_instructeur_avis_path(avis_without_answer.procedure, avis_without_answer))
         expect(dossier.commentaires.map(&:body)).to match(['commentaire body'])
+        expect(dossier.reload.last_commentaire_updated_at).to eq(now)
       end
 
       context "with a file" do
diff --git a/spec/controllers/instructeurs/dossiers_controller_spec.rb b/spec/controllers/instructeurs/dossiers_controller_spec.rb
index ec2d68386..28e8e4798 100644
--- a/spec/controllers/instructeurs/dossiers_controller_spec.rb
+++ b/spec/controllers/instructeurs/dossiers_controller_spec.rb
@@ -390,6 +390,7 @@ describe Instructeurs::DossiersController, type: :controller do
     let(:body) { "avant\napres" }
     let(:file) { fixture_file_upload('spec/fixtures/files/piece_justificative_0.pdf', 'application/pdf') }
     let(:scan_result) { true }
+    let(:now) { Timecop.freeze("09/11/1989") }
 
     subject {
       post :create_commentaire, params: {
@@ -404,14 +405,18 @@ describe Instructeurs::DossiersController, type: :controller do
 
     before do
       allow(ClamavService).to receive(:safe_file?).and_return(scan_result)
+      Timecop.freeze(now)
     end
 
+    after { Timecop.return }
+
     it "creates a commentaire" do
       expect { subject }.to change(Commentaire, :count).by(1)
       expect(instructeur.followed_dossiers).to include(dossier)
 
       expect(response).to redirect_to(messagerie_instructeur_dossier_path(dossier.procedure, dossier))
       expect(flash.notice).to be_present
+      expect(dossier.reload.last_commentaire_updated_at).to eq(now)
     end
 
     context "when the commentaire created with virus file" do
diff --git a/spec/controllers/users/dossiers_controller_spec.rb b/spec/controllers/users/dossiers_controller_spec.rb
index 9dd0cdfd5..b7a949643 100644
--- a/spec/controllers/users/dossiers_controller_spec.rb
+++ b/spec/controllers/users/dossiers_controller_spec.rb
@@ -802,6 +802,7 @@ describe Users::DossiersController, type: :controller do
     let(:body) { "avant\napres" }
     let(:file) { fixture_file_upload('spec/fixtures/files/piece_justificative_0.pdf', 'application/pdf') }
     let(:scan_result) { true }
+    let(:now) { Time.zone.parse("18/09/1981") }
 
     subject {
       post :create_commentaire, params: {
@@ -814,6 +815,7 @@ describe Users::DossiersController, type: :controller do
     }
 
     before do
+      Timecop.freeze(now)
       sign_in(user)
       allow(ClamavService).to receive(:safe_file?).and_return(scan_result)
       allow(DossierMailer).to receive(:notify_new_commentaire_to_instructeur).and_return(double(deliver_later: nil))
@@ -823,6 +825,8 @@ describe Users::DossiersController, type: :controller do
       create(:assign_to, instructeur: instructeur_without_instant_message, procedure: procedure, instant_email_message_notifications_enabled: false, groupe_instructeur: procedure.defaut_groupe_instructeur)
     end
 
+    after { Timecop.return }
+
     it "creates a commentaire" do
       expect { subject }.to change(Commentaire, :count).by(1)
 
@@ -830,6 +834,7 @@ describe Users::DossiersController, type: :controller do
       expect(DossierMailer).to have_received(:notify_new_commentaire_to_instructeur).with(dossier, instructeur_with_instant_message.email)
       expect(DossierMailer).not_to have_received(:notify_new_commentaire_to_instructeur).with(dossier, instructeur_without_instant_message.email)
       expect(flash.notice).to be_present
+      expect(dossier.reload.last_commentaire_updated_at).to eq(now)
     end
   end