diff --git a/app/services/pieces_justificatives_service.rb b/app/services/pieces_justificatives_service.rb
index 612adba3520..0fdbc2be9f2 100644
--- a/app/services/pieces_justificatives_service.rb
+++ b/app/services/pieces_justificatives_service.rb
@@ -141,11 +141,7 @@ def pjs_for_champs(dossiers)
       champs = champs.reject(&:private?)
     end
 
-    champs_id_row_index = champs.filter { _1.row_id.present? }.group_by(&:dossier_id).values.each_with_object({}) do |champs_for_dossier, hash|
-      champs_for_dossier.group_by(&:stable_id).values.each do |champs_for_stable_id|
-        champs_for_stable_id.sort_by(&:row_id).each.with_index { |c, index| hash[c.id] = index }
-      end
-    end
+    champs_id_row_index = compute_champ_id_row_index(champs)
 
     champs.flat_map do |champ|
       champ.piece_justificative_file_attachments.filter { |a| safe_attachment(a) }.map.with_index do |attachment, index|
@@ -301,4 +297,26 @@ def safe_attachment(attachment)
       .blob
       .virus_scan_result == ActiveStorage::VirusScanner::SAFE
   end
+
+  # given
+  # repet_0 (stable_id: r0)
+  # # row_0
+  # # # pj_champ_0 (stable_id: 0)
+  # # row_1
+  # # # pj_champ_1 (stable_id: 0)
+  # repet_1 (stable_id: r1)
+  # # row_0
+  # # # pj_champ_2 (stable_id: 1)
+  # # # pj_champ_3 (stable_id: 2)
+  # # row_1
+  # # # pj_champ_4 (stable_id: 1)
+  # # # pj_champ_5 (stable_id: 2)
+  # it returns { pj_0.id => 0, pj_1.id => 1, pj_2.id => 0, pj_3.id => 0, pj_4.id => 1, pj_5.id => 1 }
+  def compute_champ_id_row_index(champs)
+    champs.filter(&:child?).group_by(&:dossier_id).values.each_with_object({}) do |children_for_dossier, hash|
+      children_for_dossier.group_by(&:stable_id).values.each do |champs_for_stable_id|
+        champs_for_stable_id.sort_by(&:row_id).each.with_index { |c, index| hash[c.id] = index }
+      end
+    end
+  end
 end
diff --git a/spec/services/pieces_justificatives_service_spec.rb b/spec/services/pieces_justificatives_service_spec.rb
index 56917eda76c..dfdaa3f9428 100644
--- a/spec/services/pieces_justificatives_service_spec.rb
+++ b/spec/services/pieces_justificatives_service_spec.rb
@@ -417,6 +417,69 @@ def attachments(champ) = champ.piece_justificative_file.attachments
     end
   end
 
+  describe '#compute_champ_id_row_index' do
+    let(:user_profile) { build(:administrateur) }
+    let(:types_de_champ_public) do
+      [
+        { type: :repetition, children: [{ type: :piece_justificative }] },
+        { type: :repetition, children: [{ type: :piece_justificative }, { type: :piece_justificative }] }
+      ]
+    end
+
+    let(:procedure) { create(:procedure, types_de_champ_public:) }
+    let(:dossier_1) { create(:dossier, procedure:) }
+    let(:champs) { dossier_1.champs }
+
+    def pj_champ(d) = d.champs_public.find_by(type: 'Champs::PieceJustificativeChamp')
+    def repetition(d, index:) = d.champs_public.filter(&:repetition?)[index]
+
+    subject { PiecesJustificativesService.new(user_profile:, export_template: nil).send(:compute_champ_id_row_index, champs) }
+
+    before do
+      pj_champ(dossier_1)
+
+      # repet_0 (stable_id: r0)
+      # # row_0
+      # # # pj_champ_0 (stable_id: 0)
+      # # row_1
+      # # # pj_champ_1 (stable_id: 0)
+      # repet_1 (stable_id: r1)
+      # # row_0
+      # # # pj_champ_2 (stable_id: 1)
+      # # # pj_champ_3 (stable_id: 2)
+      # # row_1
+      # # # pj_champ_4 (stable_id: 1)
+      # # # pj_champ_5 (stable_id: 2)
+
+      repet_0 = repetition(dossier_1, index: 0)
+      repet_1 = repetition(dossier_1, index: 1)
+
+      repet_0.add_row(dossier_1.revision)
+      repet_0.add_row(dossier_1.revision)
+
+      repet_1.add_row(dossier_1.revision)
+      repet_1.add_row(dossier_1.revision)
+    end
+
+    it do
+      champs = dossier_1.champs_public
+      repet_0 = champs[0]
+      pj_0 = repet_0.rows.first.first
+      pj_1 = repet_0.rows.second.first
+
+      repet_1 = champs[1]
+      pj_2 = repet_1.rows.first.first
+      pj_3 = repet_1.rows.first.second
+
+      pj_4 = repet_1.rows.second.first
+      pj_5 = repet_1.rows.second.second
+
+      binding.irb
+
+      is_expected.to eq({ pj_0.id => 0, pj_1.id => 1, pj_2.id => 0, pj_3.id => 0, pj_4.id => 1, pj_5.id => 1 })
+    end
+  end
+
   def attach_file_to_champ(champ, safe = true)
     attach_file(champ.piece_justificative_file, safe)
   end