diff --git a/app/middleware.py b/app/middleware.py
index e765f3b..30bdd22 100644
--- a/app/middleware.py
+++ b/app/middleware.py
@@ -28,13 +28,15 @@ class PatchMalformedJsonMiddleware(BaseHTTPMiddleware):
             # try to fix json
             try:
                 j = json.loads(body)
-                self.__fix_mac_address_list_length(j=j, size=1)
+                PatchMalformedJsonMiddleware.fix_mac_address_list_length(j=j, size=1)
+                PatchMalformedJsonMiddleware.fix_ip_address_list_length(j=j, size=1)
             except json.decoder.JSONDecodeError:
                 logger.warning(f'Malformed json received! Try to fix it.')
                 body = PatchMalformedJsonMiddleware.fix_json(body)
                 logger.debug(f'Fixed JSON: "{body}"')
                 j = json.loads(body)  # ensure json is now valid
-                j = self.__fix_mac_address_list_length(j=j, size=1)
+                PatchMalformedJsonMiddleware.fix_mac_address_list_length(j=j, size=1)
+                PatchMalformedJsonMiddleware.fix_ip_address_list_length(j=j, size=1)
                 # set new body
                 request._body = json.dumps(j).encode('utf-8')
 
@@ -42,7 +44,7 @@ class PatchMalformedJsonMiddleware(BaseHTTPMiddleware):
         return response
 
     @staticmethod
-    def __fix_mac_address_list_length(j: dict, size: int = 1) -> dict:
+    def fix_mac_address_list_length(j: dict, size: int = 1) -> dict:
         # reduce "mac_address_list" to
         environment = j.get('environment', {})
         fingerprint = environment.get('fingerprint', {})
@@ -54,6 +56,18 @@ class PatchMalformedJsonMiddleware(BaseHTTPMiddleware):
 
         return j
 
+    @staticmethod
+    def fix_ip_address_list_length(j: dict, size: int = 1) -> dict:
+        # reduce "ip_address_list" to
+        environment = j.get('environment', {})
+        ip_addresses = environment.get('ip_address_list', [])
+
+        if len(ip_addresses) > 0:
+            logger.info(f'Transforming "ip_address_list" to length of {size}.')
+            j['environment']['ip_address_list'] = ip_addresses[:size]
+
+        return j
+
     @staticmethod
     def fix_json(s: str) -> str:
         s = s.replace('\t', '')
diff --git a/test/main.py b/test/main.py
index 8f2e2c7..f35f371 100644
--- a/test/main.py
+++ b/test/main.py
@@ -114,7 +114,21 @@ def test_auth_v1_origin_malformed_json():  # see oscar.krause/fastapi-dls#1
     s = '{"environment": {"fingerprint": {"mac_address_list": [ff:ff:ff:ff:ff:ff"]}}'
     replaced = PatchMalformedJsonMiddleware.fix_json(s)
     assert replaced == '{"environment": {"fingerprint": {"mac_address_list": ["ff:ff:ff:ff:ff:ff"]}}'
- 
+
+
+def test_auth_v1_origin_middleware():  # see oscar.krause/fastapi-dls#1
+    import json
+    from middleware import PatchMalformedJsonMiddleware
+
+    # test regex (temporary, until this section is merged into main.py
+    s = '{"environment": {"fingerprint": {"mac_address_list": ["aa:aa:aa:aa:aa:aa", "bb:bb:bb:bb:bb:bb"]}, "ip_address_list": ["127.0.0.1", "127.0.0.2"]}}'
+    j = json.loads(s)
+    PatchMalformedJsonMiddleware.fix_mac_address_list_length(j=j, size=1)
+    PatchMalformedJsonMiddleware.fix_ip_address_list_length(j=j, size=1)
+    s = json.dumps(j)
+    assert s == '{"environment": {"fingerprint": {"mac_address_list": ["aa:aa:aa:aa:aa:aa"]}, "ip_address_list": ["127.0.0.1"]}}'
+
+
 
 def auth_v1_origin_update():
     payload = {