diff --git a/app/services/piece_justificative_to_champ_piece_jointe_migration_service.rb b/app/services/piece_justificative_to_champ_piece_jointe_migration_service.rb
index 48b228266..69cebd114 100644
--- a/app/services/piece_justificative_to_champ_piece_jointe_migration_service.rb
+++ b/app/services/piece_justificative_to_champ_piece_jointe_migration_service.rb
@@ -85,8 +85,10 @@ class PieceJustificativeToChampPieceJointeMigrationService
         )
       else
         champ.update_columns(
-          updated_at: dossier.updated_at,
-          created_at: dossier.created_at
+          created_at: dossier.created_at,
+          # Set an updated_at date that won't cause notifications to appear
+          # on gestionnaires' dashboard.
+          updated_at: dossier.created_at
         )
       end
 
diff --git a/spec/services/piece_justificative_to_champ_piece_jointe_migration_service_spec.rb b/spec/services/piece_justificative_to_champ_piece_jointe_migration_service_spec.rb
index df63d3014..48b60b32b 100644
--- a/spec/services/piece_justificative_to_champ_piece_jointe_migration_service_spec.rb
+++ b/spec/services/piece_justificative_to_champ_piece_jointe_migration_service_spec.rb
@@ -113,9 +113,9 @@ describe PieceJustificativeToChampPieceJointeMigrationService do
           dossier.reload
         end
 
-        it 'the champ has the same timestamps as the dossier' do
+        it 'the champ doesn’t trigger a notification' do
           expect(dossier.champs.last.created_at).to eq(initial_dossier_timestamps[:created_at])
-          expect(dossier.champs.last.updated_at).to eq(initial_dossier_timestamps[:updated_at])
+          expect(dossier.champs.last.updated_at).to eq(initial_dossier_timestamps[:created_at])
         end
 
         it 'does not change the dossier timestamps' do