diff --git a/README.md b/README.md
index f5934f0..ab1bd4e 100644
--- a/README.md
+++ b/README.md
@@ -103,7 +103,11 @@ properties["mrr"] = 399
 properties["plan"] = "Pro"
 properties["registered_at"] = datetime.now()
 properties["this_property_will_be_deleted"] = ""
-result = client.upsert_account(account, properties, ["memberId1", "memberId2"])
+
+member1 = UserIdentified.by_user_id("memberId1")
+member2 = UserIdentified.by_user_id("memberId2")
+
+result = client.upsert_account(account, properties, [member1, member2])
 if isinstance(result, Success):
     print(result.request_id)  # str
     print(result.calls_remaining)  # int
diff --git a/journyio/client.py b/journyio/client.py
index 59464cb..210327d 100644
--- a/journyio/client.py
+++ b/journyio/client.py
@@ -12,6 +12,7 @@
 from .user_identified import UserIdentified
 from .account_identified import AccountIdentified
 
+
 class Properties(dict):
 
     def __init__(self):
@@ -149,12 +150,13 @@ def upsert_user(self, user: UserIdentified, properties: Properties) -> Success[N
         except Exception:
             raise JournyException(f"An unknown error has occurred")
 
-    def upsert_account(self, account: AccountIdentified, properties: Properties, members: List[str]) -> Success[
-                                                                                                              None] or Failure:
+    def upsert_account(self, account: AccountIdentified, properties: Properties, members: List[UserIdentified]) -> \
+        Success[
+            None] or Failure:
         assert_journy(isinstance(account, AccountIdentified), "Account is not an AccountIdentified object.")
         assert_journy(isinstance(properties, Properties), "Properties is not a Properties object.")
         for member in members:
-            assert_journy(isinstance(member, str), f"Member {member} is not a string.")
+            assert_journy(isinstance(member, UserIdentified), f"Member {member} is not a UserIdentified object.")
 
         try:
             request = HttpRequest(self.__create_url("/accounts/upsert"), Method.POST,
@@ -162,7 +164,8 @@ def upsert_account(self, account: AccountIdentified, properties: Properties, mem
                                   json.dumps({
                                       "identification": account.format_identification(),
                                       "properties": properties.properties,
-                                      "members": members
+                                      "members": [{"identification": member.format_identification()} for member in
+                                                  members]
                                   }))
             response = self.httpclient.send(request)
             calls_remaining = Client.__parse_calls_remaining(response)
diff --git a/tests/test_client.py b/tests/test_client.py
index 500bb2d..4c5f47d 100644
--- a/tests/test_client.py
+++ b/tests/test_client.py
@@ -154,7 +154,10 @@ def test_client_upsert_account():
     properties["haveDog"] = False
     properties["name"] = "Journy"
 
-    response = client.upsert_account(account, properties, ["hansId", "manuId"])
+    member1 = UserIdentified.by_user_id("hansId")
+    member2 = UserIdentified.by_user_id("manuId")
+
+    response = client.upsert_account(account, properties, [member1, member2])
 
     assert (isinstance(response, Success))
     assert (response.__str__() == "Success(requestId, 4999, None)")
@@ -163,7 +166,7 @@ def test_client_upsert_account():
     assert (response.data is None)
 
     assert (
-        http_client_testing.received_request.__str__() == 'HttpRequest(https://api.journy.io/accounts/upsert, Method.POST, {"content-type": "application/json", "x-api-key": "api-key"}, {"identification": {"domain": "www.journy.io", "accountId": "account_id"}, "properties": {"havedog": false, "name": "Journy"}, "members": ["hansId", "manuId"]})')
+        http_client_testing.received_request.__str__() == 'HttpRequest(https://api.journy.io/accounts/upsert, Method.POST, {"content-type": "application/json", "x-api-key": "api-key"}, {"identification": {"domain": "www.journy.io", "accountId": "account_id"}, "properties": {"havedog": false, "name": "Journy"}, "members": [{"identification": {"userId": "hansId"}}, {"identification": {"userId": "manuId"}}]})')
 
 
 def test_client_link():