diff --git a/src/pyopenweathermap/client/onecall_client.py b/src/pyopenweathermap/client/onecall_client.py
index 078a8ec..cff548e 100644
--- a/src/pyopenweathermap/client/onecall_client.py
+++ b/src/pyopenweathermap/client/onecall_client.py
@@ -44,7 +44,10 @@ async def validate_key(self) -> bool:
             return False
 
     def _get_url(self, lat, lon):
-        return (f"{API_URL}?"
+        api_url = 'https://api.openweathermap.org/data/3.0/onecall'
+        if getattr(self, 'api_version', None) == 'v4.0':
+            api_url = 'https://api.openweathermap.org/data/4.0/onecall'
+        return (f"{api_url}?"
                 f"lat={lat}&"
                 f"lon={lon}&"
                 f"appid={self.api_key}&"
diff --git a/src/pyopenweathermap/client/owm_client_factory.py b/src/pyopenweathermap/client/owm_client_factory.py
index e4523fb..34a11d4 100644
--- a/src/pyopenweathermap/client/owm_client_factory.py
+++ b/src/pyopenweathermap/client/owm_client_factory.py
@@ -9,7 +9,7 @@ def create_owm_client(api_key, api_type, units="metric", lang='en'):
     logger = logging.getLogger(__name__)
     
     logger.info('Initializing OWMClient with api type: ' + str(api_type))
-    if api_type == 'v3.0':
+    if api_type == 'v3.0' or api_type == 'v4.0':
         return OWMOneCallClient(api_key, api_type, units, lang)
     if api_type == 'current' or api_type == 'forecast':
         return OWMFreeClient(api_key, api_type, units, lang)
diff --git a/tests/test_all.py b/tests/test_all.py
index a5d9f5f..f2c59b3 100644
--- a/tests/test_all.py
+++ b/tests/test_all.py
@@ -20,6 +20,16 @@ async def test_api_30():
     assert report.daily_forecast[0].condition.id is not None
     
     
+@pytest.mark.network
+@pytest.mark.asyncio
+async def test_api_40():
+    api_key = os.getenv('OWM_API_KEY')
+    client = create_owm_client(api_key, 'v4.0')
+    report = await client.get_weather(LATITUDE, LONGITUDE)
+    assert report.current.date_time is not None
+    assert report.hourly_forecast[0].condition.id is not None
+    assert report.daily_forecast[0].condition.id is not None
+    
 @pytest.mark.network
 @pytest.mark.asyncio
 async def test_free_current_weather():
@@ -115,3 +125,9 @@ def test_forecast_deserialization():
     weather = DataConverter.free_to_hourly_weather_forecast(data)
     assert weather.date_time is not None
     assert weather.condition.id is not None
+
+def test_v40_url():
+    client = create_owm_client('fake_key', 'v4.0')
+    url = client._get_url(10.0, 20.0)
+    assert 'https://api.openweathermap.org/data/4.0/onecall' in url
+    assert 'fake_key' in url