diff --git a/passerelle/apps/smsfactor/models.py b/passerelle/apps/smsfactor/models.py
index e3c71066..010957bf 100644
--- a/passerelle/apps/smsfactor/models.py
+++ b/passerelle/apps/smsfactor/models.py
@@ -171,7 +171,8 @@ class SMSFactorSMSGateway(SMSResource):
     def update_credit_left(self):
         result = self.request('get', endpoint='credits')
         try:
-            self.credit_left = result['credits']
+            # SMS Factor returns this as a string, for an unknown reason
+            self.credit_left = int(result['credits'])
         except KeyError:
             self.logger.warning('Cannot retrieve credits for sms-factor connector: %s', result)
         else:
diff --git a/tests/test_sms.py b/tests/test_sms.py
index 750c3d1a..fb6164b8 100644
--- a/tests/test_sms.py
+++ b/tests/test_sms.py
@@ -788,13 +788,13 @@ def test_sms_factor_alert_emails(app, freezer, mailoutbox):
     )
 
     freezer.move_to('2019-01-01 00:00:00')
-    resp = {'credits': 101}
+    resp = {'credits': "101"}
     url = connector.URL
     with tests.utils.mock_url(url, resp, 200):
         connector.hourly()
     assert len(mailoutbox) == 0
 
-    resp = {'credits': 99}
+    resp = {'credits': "99"}
     url = connector.URL
     with tests.utils.mock_url(url, resp, 200):
         connector.hourly()