diff --git a/pydantic_settings/main.py b/pydantic_settings/main.py
index 2aab9b95..d28975ae 100644
--- a/pydantic_settings/main.py
+++ b/pydantic_settings/main.py
@@ -85,6 +85,7 @@ def _settings_build_values(
             ),
             env_prefix_len=len(self.model_config.get('env_prefix', '')),
         )
+        # self.__env_settings__ = env_settings
         dotenv_settings = DotEnvSettingsSource(
             self.__class__,
             env_file=(_env_file if _env_file != env_file_sentinel else self.model_config.get('env_file')),
diff --git a/pydantic_settings/sources.py b/pydantic_settings/sources.py
index 5dd9db32..612394bd 100644
--- a/pydantic_settings/sources.py
+++ b/pydantic_settings/sources.py
@@ -4,15 +4,16 @@
 import os
 import warnings
 from abc import ABC, abstractmethod
+from collections import deque
 from dataclasses import is_dataclass
 from pathlib import Path
-from typing import TYPE_CHECKING, Any, Dict, List, Mapping, Optional, Tuple, Type, Union
+from typing import TYPE_CHECKING, Any, Dict, List, Mapping, Optional, Sequence, Tuple, Type, Union
 
 from pydantic import BaseModel
 from pydantic._internal._typing_extra import origin_is_union
 from pydantic._internal._utils import deep_update, lenient_issubclass
 from pydantic.fields import FieldInfo
-from typing_extensions import get_origin
+from typing_extensions import get_args, get_origin
 
 from pydantic_settings.utils import path_type_label
 
@@ -53,10 +54,18 @@ def get_field_value(self, field: FieldInfo, field_name: str) -> Tuple[Any, str,
         pass
 
     def field_is_complex(self, field: FieldInfo) -> bool:
-        def _annotation_is_complex(annotation: type[Any] | None) -> bool:
-            return lenient_issubclass(annotation, (BaseModel, list, set, frozenset, dict)) or is_dataclass(annotation)
+        """
+        Checks whether a field is complex, in which case it will attempt to be parsed as JSON.
+
+        Args:
+            field (FieldInfo): The field.
 
-        return _annotation_is_complex(field.annotation) or _annotation_is_complex(get_origin(field.annotation))
+        Returns:
+            bool: Whether the field is complex.
+        """
+        result = _annotation_is_complex(field.annotation)
+        print(result, field.annotation)
+        return result
 
     def prepare_field_value(self, field_name: str, field: FieldInfo, value: Any, value_is_complex: bool) -> Any:
         """
@@ -433,3 +442,22 @@ def find_case_path(dir_path: Path, file_name: str, case_sensitive: bool) -> Opti
         elif not case_sensitive and f.name.lower() == file_name.lower():
             return f
     return None
+
+
+def _annotation_is_complex(annotation: type[Any] | None) -> bool:
+    origin = get_origin(annotation)
+    return (
+        _annotation_is_complex_inner(annotation)
+        or _annotation_is_complex_inner(origin)
+        or hasattr(origin, '__pydantic_core_schema__')
+        or hasattr(origin, '__get_pydantic_core_schema__')
+    )
+
+
+def _annotation_is_complex_inner(annotation: type[Any] | None) -> bool:
+    if lenient_issubclass(annotation, str):
+        return False
+
+    return lenient_issubclass(annotation, (BaseModel, Mapping, Sequence, tuple, set, frozenset, deque)) or is_dataclass(
+        annotation
+    )
diff --git a/tests/test_settings.py b/tests/test_settings.py
index f431616b..1c1b38d5 100644
--- a/tests/test_settings.py
+++ b/tests/test_settings.py
@@ -622,6 +622,10 @@ class B(BaseSettings):
     class Settings(BaseSettings):
         content: Union[A, B, datetime]
 
+    env.set('content', '{"a": "test"}')
+    s = Settings()
+    assert s.content == A(a='test')
+
     env.set('content', '2020-07-05T00:00:00Z')
     s = Settings()
     assert s.content == datetime(2020, 7, 5, 0, 0, tzinfo=timezone.utc)