diff --git a/src/aerovaldb/jsondb/jsonfiledb.py b/src/aerovaldb/jsondb/jsonfiledb.py
index fdb290d..d97d52d 100644
--- a/src/aerovaldb/jsondb/jsonfiledb.py
+++ b/src/aerovaldb/jsondb/jsonfiledb.py
@@ -37,8 +37,10 @@ def json_dumps_wrapper(obj, **kwargs) -> str:
     """
     Wrapper which calls simplejson.dumps with the correct options, known to work for objects
     returned by Pyaerocom.
+
+    This ensures that nan values are serialized as null to be compliant with the json standard.
     """
-    return simplejson.dumps(obj, allow_nan=True, **kwargs)
+    return simplejson.dumps(obj, ignore_nan=True, **kwargs)
 
 
 class AerovalJsonFileDB(AerovalDB):
diff --git a/tests/jsondb/test_jsonfiledb.py b/tests/jsondb/test_jsonfiledb.py
index 46df488..1e2b12b 100644
--- a/tests/jsondb/test_jsonfiledb.py
+++ b/tests/jsondb/test_jsonfiledb.py
@@ -356,7 +356,7 @@ def test_write_and_read_of_nan(tmp_path):
 
         read = db.get_by_uri("./test")
 
-        assert math.isnan(read["value"])
+        assert read["value"] is None
 
 
 def test_exception_on_unexpected_args():