diff --git a/passerelle/apps/esup_signature/models.py b/passerelle/apps/esup_signature/models.py
index d99581a9..af210ce7 100644
--- a/passerelle/apps/esup_signature/models.py
+++ b/passerelle/apps/esup_signature/models.py
@@ -140,12 +140,12 @@ class EsupSignature(BaseResource, HTTPResource):
     class Meta:
         verbose_name = _('Esup Signature')
 
-    def _call(self, path, method='get', data=None, files=None, expect_json=True):
+    def _call(self, path, method='get', params=None, files=None, expect_json=True):
         url = urllib.parse.urljoin(self.base_url, path)
         kwargs = {}
 
         if method == 'post':
-            kwargs['data'] = data
+            kwargs['params'] = params
             kwargs['files'] = files
 
         try:
@@ -206,7 +206,7 @@ class EsupSignature(BaseResource, HTTPResource):
             )
         }
 
-        data = {
+        params = {
             'signType': 'pdfImageStamp',
             'recipientsEmails': clean_list(post_data['recipients_emails']),
             'eppn': post_data['eppn'],
@@ -214,7 +214,7 @@ class EsupSignature(BaseResource, HTTPResource):
             'pending': True,
         }
 
-        return {'data': self._call('ws/signrequests/new', method='post', data=data, files=files)}
+        return {'data': self._call('ws/signrequests/new', method='post', params=params, files=files)}
 
     @endpoint(
         name='new-with-workflow',
@@ -263,7 +263,7 @@ class EsupSignature(BaseResource, HTTPResource):
             )
         }
 
-        data = {
+        params = {
             'createByEppn': post_data['eppn'],
             'title': post_data.get('title', ''),
             'recipientsEmails': clean_list(post_data.get('recipients_emails', [])),
@@ -275,7 +275,7 @@ class EsupSignature(BaseResource, HTTPResource):
 
         return {
             'data': self._call(
-                '/ws/workflows/%s/new' % post_data['workflow_id'], method='post', data=data, files=files
+                '/ws/workflows/%s/new' % post_data['workflow_id'], method='post', params=params, files=files
             )
         }
 
diff --git a/tests/test_esup_signature.py b/tests/test_esup_signature.py
index 36c85a38..b6411c02 100644
--- a/tests/test_esup_signature.py
+++ b/tests/test_esup_signature.py
@@ -35,7 +35,19 @@ def test_new(app, connector):
         'title': 'a title',
     }
     with responses.RequestsMock() as rsps:
-        rsps.post('https://esup-signature.invalid/ws/signrequests/new', status=200, json=9)
+        query_params = {
+            'recipientsEmails': ['foo@invalid', 'bar@invalid'],
+            'eppn': 'baz@invalid',
+            'title': 'a title',
+            'signType': 'pdfImageStamp',
+            'pending': True,
+        }
+        rsps.post(
+            'https://esup-signature.invalid/ws/signrequests/new',
+            match=[responses.matchers.query_param_matcher(query_params)],
+            status=200,
+            json=9,
+        )
         resp = app.post_json('/esup-signature/esup-signature/new', params=params)
         assert len(rsps.calls) == 1
         assert rsps.calls[0].request.headers['Content-Type'].startswith('multipart/form-data')
@@ -68,7 +80,22 @@ def test_new_with_workflow(app, connector):
         'target_urls/1': 'smb://foo.bar/location-2/',
     }
     with responses.RequestsMock() as rsps:
-        rsps.post('https://esup-signature.invalid/ws/workflows/99/new', status=200, json=9)
+        query_params = {
+            'createByEppn': 'aa@foo.com',
+            'title': 'a title',
+            'recipientsEmails': ['0*xx@foo.com', '0*yy@foo.com', '1*zz@foo.com'],
+            'allSignToCompletes': ['12', '13'],
+            'targetEmails': ['xx@foo.com', 'yy@foo.com', 'zz@foo.com'],
+            'signRequestParamsJsonString': 'List [ OrderedMap { "xPos": 100, "yPos": 100, "signPageNumber": 1 }, '
+            'OrderedMap { "xPos": 200, "yPos": 200, "signPageNumber": 1 } ]',
+            'targetUrls': ['smb://foo.bar/location-1/', 'smb://foo.bar/location-2/'],
+        }
+        rsps.post(
+            'https://esup-signature.invalid/ws/workflows/99/new',
+            match=[responses.matchers.query_param_matcher(query_params)],
+            status=200,
+            json=9,
+        )
         resp = app.post_json('/esup-signature/esup-signature/new-with-workflow', params=params)
         assert len(rsps.calls) == 1
         assert rsps.calls[0].request.headers['Content-Type'].startswith('multipart/form-data')