diff --git a/neon_api_proxy/services/owm_api.py b/neon_api_proxy/services/owm_api.py
index b5b5973..2e6d7f7 100644
--- a/neon_api_proxy/services/owm_api.py
+++ b/neon_api_proxy/services/owm_api.py
@@ -92,6 +92,7 @@ def _get_api_response(self, lat: str, lng: str, units: str,
                             f"is supported", "1.0.0")
             api = "onecall"
         assert units in ("metric", "imperial", "standard")
+        lang = lang.split('-')[0]  # `de-de` is treated as `en`
         query_params = {"lat": lat,
                         "lon": lng,
                         "appid": self._api_key,
diff --git a/tests/test_owm_api.py b/tests/test_owm_api.py
index b9fa42f..d9a56f0 100644
--- a/tests/test_owm_api.py
+++ b/tests/test_owm_api.py
@@ -49,6 +49,16 @@
                "lng": "-122.2060",
                "units": "imperial"}
 
+VALID_QUERY_ES = {"lat": "47.6769",
+                  "lng": "-122.2060",
+                  "units": "imperial",
+                  "lang": "es"}
+
+VALID_QUERY_ES_MX = {"lat": "47.6769",
+                     "lng": "-122.2060",
+                     "units": "imperial",
+                     "lang": "es-mx"}
+
 VALID_QUERY_ONECALL = {"lat": "47.6769",
                        "lng": "-122.2060",
                        "units": "imperial",
@@ -105,6 +115,15 @@ def test_handle_query_valid(self):
         self.assertEqual(resp["encoding"], "utf-8")
         self.assertIsInstance(json.loads(resp["content"]), dict)
 
+        resp_es = self.api.handle_query(**VALID_QUERY_ES)
+        self.assertEqual(resp_es["status_code"], 200)
+        self.assertEqual(resp_es["encoding"], "utf-8")
+        self.assertIsInstance(json.loads(resp_es["content"]), dict)
+        self.assertNotEqual(resp, resp_es)
+
+        resp_es_mx = self.api.handle_query(**VALID_QUERY_ES_MX)
+        self.assertEqual(resp_es, resp_es_mx)
+
     def test_handle_query_valid_onecall(self):
         resp = self.api.handle_query(**VALID_QUERY_ONECALL)
         self.assertIsInstance(resp, dict)