diff --git a/superset/utils/core.py b/superset/utils/core.py
index 14ec121de4c20..3f998ca1585e6 100644
--- a/superset/utils/core.py
+++ b/superset/utils/core.py
@@ -211,7 +211,7 @@ def parse_js_uri_path_item(
     return unquote_plus(item) if unquote and item else item
 
 
-def cast_to_num(value: Union[float, int, str]) -> Optional[Union[float, int]]:
+def cast_to_num(value: Optional[Union[float, int, str]]) -> Optional[Union[float, int]]:
     """Casts a value to an int/float
 
     >>> cast_to_num('5')
@@ -222,6 +222,8 @@ def cast_to_num(value: Union[float, int, str]) -> Optional[Union[float, int]]:
     10
     >>> cast_to_num(10.1)
     10.1
+    >>> cast_to_num(None) is None
+    True
     >>> cast_to_num('this is not a string') is None
     True
 
@@ -229,6 +231,8 @@ def cast_to_num(value: Union[float, int, str]) -> Optional[Union[float, int]]:
     :returns: value cast to `int` if value is all digits, `float` if `value` is
               decimal value and `None`` if it can't be converted
     """
+    if value is None:
+        return None
     if isinstance(value, (int, float)):
         return value
     if value.isdigit():
diff --git a/tests/utils_tests.py b/tests/utils_tests.py
index 7cb32b729b1a9..4d7806448af16 100644
--- a/tests/utils_tests.py
+++ b/tests/utils_tests.py
@@ -38,6 +38,7 @@
 from superset.utils.cache_manager import CacheManager
 from superset.utils.core import (
     base_json_conv,
+    cast_to_num,
     convert_legacy_filters_into_adhoc,
     create_ssl_cert_file,
     format_timedelta,
@@ -1368,6 +1369,14 @@ def test_schema_one_of_case_insensitive(self):
         self.assertRaises(marshmallow.ValidationError, validator, "qwerty")
         self.assertRaises(marshmallow.ValidationError, validator, 4)
 
+    def test_cast_to_num(self) -> None:
+        assert cast_to_num("5") == 5
+        assert cast_to_num("5.2") == 5.2
+        assert cast_to_num(10) == 10
+        assert cast_to_num(10.1) == 10.1
+        assert cast_to_num(None) is None
+        assert cast_to_num("this is not a string") is None
+
     def test_get_form_data_token(self):
         assert get_form_data_token({"token": "token_abcdefg1"}) == "token_abcdefg1"
         generated_token = get_form_data_token({})