diff --git a/churchtools_api/persons.py b/churchtools_api/persons.py
index dea0409..50c9ff2 100644
--- a/churchtools_api/persons.py
+++ b/churchtools_api/persons.py
@@ -92,6 +92,8 @@ def get_persons_masterdata(
         """Function to get the Masterdata of the persons module.
 
         This information is required to map some IDs to specific items.
+        Special case treatment for resultClass sexes
+            first item is copied for "None" references as fallback
 
         Arguments:
             resultClass: the name of the masterdata to retrieve. Defaults to All
@@ -111,8 +113,11 @@ def get_persons_masterdata(
 
             if resultClass:
                 response_data = response_data[resultClass]
+                if resultClass == "sexes":
+                    response_data.insert(0, {**response_data[0], "id": None})
                 if returnAsDict:
                     response_data = {item["id"]: item["name"] for item in response_data}
+                    response_data[None] = response_data[0]
 
             logger.debug("Person Masterdata load successful len=%s", len(response_data))
 
diff --git a/tests/test_churchtools_api_persons.py b/tests/test_churchtools_api_persons.py
index 55f14ce..54b026f 100644
--- a/tests/test_churchtools_api_persons.py
+++ b/tests/test_churchtools_api_persons.py
@@ -111,10 +111,25 @@ def test_get_persons_sex_id(self) -> None:
         EXPECTED_RESULT = "sex.unknown"
         SAMPLE_USER_ID = 513
 
-        person = self.api.get_persons(ids=[SAMPLE_USER_ID])
+        person = self.api.get_persons(ids=[SAMPLE_USER_ID])[0]
         gender_map = self.api.get_persons_masterdata(
             resultClass="sexes", returnAsDict=True
         )
-        result = gender_map[person[0]["sexId"]]
+        result = gender_map[person["sexId"]]
+
+        assert result == EXPECTED_RESULT
+
+    def test_get_persons_sex_id_none(self) -> None:
+        """Tests that persons sexId can be converted if NULL.
+
+        IMPORTANT - This test method and the parameters used depend on target system!
+        the hard coded sample exists on ELKW1610.KRZ.TOOLS
+        """
+        EXPECTED_RESULT = "sex.unknown"
+
+        gender_map = self.api.get_persons_masterdata(
+            resultClass="sexes", returnAsDict=True
+        )
+        result = gender_map[None]
 
         assert result == EXPECTED_RESULT