diff --git a/dlt/common/normalizers/json/relational.py b/dlt/common/normalizers/json/relational.py
index d89cd59224..d2255512bc 100644
--- a/dlt/common/normalizers/json/relational.py
+++ b/dlt/common/normalizers/json/relational.py
@@ -1,4 +1,5 @@
 from functools import lru_cache, partial
+from importlib import import_module
 from typing import (
     ClassVar,
     Dict,
@@ -37,6 +38,7 @@
 )
 from dlt.common.utils import update_dict_nested
 from dlt.common.normalizers.json import (
+    SupportsDataItemNormalizer,
     TNormalizedRowIterator,
     wrap_in_dict,
     DataItemNormalizer as DataItemNormalizerBase,
@@ -332,7 +334,7 @@ def extend_schema(self, extend_tables: bool = True) -> None:
             RelationalNormalizerConfig,
             self.schema._normalizers_config["json"].get("config") or {},
         )
-        DataItemNormalizer._validate_normalizer_config(self.schema, config)
+        self._validate_normalizer_config(self.schema, config)
 
         # add hints, do not compile.
         self.schema._merge_hints(
@@ -433,7 +435,8 @@ def normalize_data_item(
     def ensure_this_normalizer(cls, norm_config: TJSONNormalizer) -> None:
         # make sure schema has right normalizer
         present_normalizer = norm_config["module"]
-        if present_normalizer != cls.__module__:
+        module = cast(SupportsDataItemNormalizer, import_module(present_normalizer))
+        if not issubclass(module.DataItemNormalizer, cls):
             raise InvalidJsonNormalizer(cls.__module__, present_normalizer)
 
     @classmethod
diff --git a/dlt/common/schema/normalizers.py b/dlt/common/schema/normalizers.py
index 7552c6931e..296cbfd784 100644
--- a/dlt/common/schema/normalizers.py
+++ b/dlt/common/schema/normalizers.py
@@ -8,8 +8,8 @@
 from dlt.common import known_env
 from dlt.common.configuration.inject import with_config
 from dlt.common.configuration.specs import known_sections
-from dlt.common.schema.configuration import SchemaConfiguration
 from dlt.common.normalizers.exceptions import InvalidJsonNormalizer
+from dlt.common.schema.configuration import SchemaConfiguration
 from dlt.common.normalizers.json import SupportsDataItemNormalizer, DataItemNormalizer
 from dlt.common.normalizers.naming import NamingConvention
 from dlt.common.normalizers.naming.exceptions import (
@@ -114,12 +114,13 @@ def import_normalizers(
 
         try:
             DataItemNormalizer.ensure_this_normalizer(item_normalizer)
+            
             item_normalizer.setdefault("config", {})
             item_normalizer["config"]["max_nesting"] = destination_capabilities.max_table_nesting  # type: ignore[index]
         except InvalidJsonNormalizer:
             # not a right normalizer
             logger.warning(f"JSON Normalizer {item_normalizer} does not support max_nesting")
-            pass
+
     json_module = cast(SupportsDataItemNormalizer, import_module(json_module_name))
     explicit_normalizers["json"] = item_normalizer
     return (