diff --git a/app/jobs/cron/operations_signature_job.rb b/app/jobs/cron/operations_signature_job.rb
index 605cea3334d..6985ac04034 100644
--- a/app/jobs/cron/operations_signature_job.rb
+++ b/app/jobs/cron/operations_signature_job.rb
@@ -2,14 +2,17 @@ class Cron::OperationsSignatureJob < Cron::CronJob
   self.schedule_expression = "every day at 6 am"
 
   def perform(*args)
+    start_date = DossierOperationLog.where(bill_signature: nil).order(:executed_at).pick(:executed_at).beginning_of_day
     last_midnight = Time.zone.today.beginning_of_day
-    operations_by_day = BillSignatureService.grouped_unsigned_operation_until(last_midnight)
-    operations_by_day.each do |day, operations|
-      begin
-        BillSignatureService.sign_operations(operations, day)
-      rescue
-        raise # let errors show up on Sentry and delayed_jobs
-      end
+
+    while start_date < last_midnight
+      operations = DossierOperationLog
+        .select(:id, :digest)
+        .where(executed_at: start_date...start_date.tomorrow, bill_signature: nil)
+
+      BillSignatureService.sign_operations(operations, start_date) if operations.present?
+
+      start_date = start_date.tomorrow
     end
   end
 end
diff --git a/app/services/bill_signature_service.rb b/app/services/bill_signature_service.rb
index 7badb339980..685355e7b35 100644
--- a/app/services/bill_signature_service.rb
+++ b/app/services/bill_signature_service.rb
@@ -1,12 +1,4 @@
 class BillSignatureService
-  def self.grouped_unsigned_operation_until(date)
-    date = date.in_time_zone
-    unsigned_operations = DossierOperationLog
-      .where(bill_signature: nil)
-      .where('executed_at < ?', date)
-    unsigned_operations.group_by { |e| e.executed_at.to_date }
-  end
-
   def self.sign_operations(operations, day)
     return unless Certigna::API.enabled?
     bill = BillSignature.build_with_operations(operations, day)
diff --git a/spec/jobs/cron/operations_signature_job_spec.rb b/spec/jobs/cron/operations_signature_job_spec.rb
new file mode 100644
index 00000000000..94ce99f8202
--- /dev/null
+++ b/spec/jobs/cron/operations_signature_job_spec.rb
@@ -0,0 +1,40 @@
+RSpec.describe Cron::OperationsSignatureJob, type: :job do
+  describe 'perform' do
+    subject { Cron::OperationsSignatureJob.perform_now }
+
+    let(:today) { Time.zone.parse('2018-01-05 00:06:00') }
+
+    before do
+      travel_to(today)
+      allow(BillSignatureService).to receive(:sign_operations)
+    end
+
+    context "with dol without signature executed_at two_days_ago" do
+      let(:two_days_ago_00_30) { Time.zone.parse('2018-01-03 00:30:00') }
+      let(:two_days_ago_00_00) { Time.zone.parse('2018-01-03 00:00:00') }
+
+      let(:one_day_ago_00_30) { Time.zone.parse('2018-01-04 00:30:00') }
+      let(:one_day_ago_00_00) { Time.zone.parse('2018-01-04 00:00:00') }
+
+      let!(:dol_1) { create(:dossier_operation_log, executed_at: two_days_ago_00_30) }
+      let!(:dol_2) { create(:dossier_operation_log, executed_at: one_day_ago_00_30) }
+
+      before { subject }
+
+      it do
+        expect(BillSignatureService).to have_received(:sign_operations).exactly(2).times
+        expect(BillSignatureService).to have_received(:sign_operations).with([dol_1], two_days_ago_00_00)
+        expect(BillSignatureService).to have_received(:sign_operations).with([dol_2], one_day_ago_00_00)
+      end
+    end
+
+    context "with dol without signature executed_at today past midnight" do
+      let(:today_00_01) { Time.zone.parse('2018-01-05 00:00:01') }
+      let!(:dol) { create(:dossier_operation_log, executed_at: today_00_01) }
+
+      before { subject }
+
+      it { expect(BillSignatureService).not_to have_received(:sign_operations) }
+    end
+  end
+end
diff --git a/spec/services/bill_signature_service_spec.rb b/spec/services/bill_signature_service_spec.rb
index e9a0866acaa..7f4f8c08134 100644
--- a/spec/services/bill_signature_service_spec.rb
+++ b/spec/services/bill_signature_service_spec.rb
@@ -1,38 +1,4 @@
 describe BillSignatureService do
-  describe ".grouped_unsigned_operation_until" do
-    subject { BillSignatureService.grouped_unsigned_operation_until(date).length }
-
-    let(:date) { Time.zone.now.beginning_of_day }
-
-    context "when operations of several days need to be signed" do
-      before do
-        create :dossier_operation_log, executed_at: 3.days.ago
-        create :dossier_operation_log, executed_at: 2.days.ago
-        create :dossier_operation_log, executed_at: 1.day.ago
-      end
-
-      it { is_expected.to eq 3 }
-    end
-
-    context "when operations on a single day need to be signed" do
-      before do
-        create :dossier_operation_log, executed_at: 1.day.ago
-        create :dossier_operation_log, executed_at: 1.day.ago
-      end
-
-      it { is_expected.to eq 1 }
-    end
-
-    context "when there are no operations to be signed" do
-      before do
-        create :dossier_operation_log, created_at: 1.day.ago, bill_signature: build(:bill_signature, :with_signature, :with_serialized)
-        create :dossier_operation_log, created_at: 1.day.from_now
-      end
-
-      it { is_expected.to eq 0 }
-    end
-  end
-
   describe ".sign_operations" do
     let(:date) { Date.today }