diff --git a/aiopenapi3/base.py b/aiopenapi3/base.py
index 3a69f5f6..60af5d1b 100644
--- a/aiopenapi3/base.py
+++ b/aiopenapi3/base.py
@@ -18,7 +18,7 @@
 else:
     from typing_extensions import TypeGuard
 
-from pydantic import BaseModel, Field, AnyUrl, model_validator, PrivateAttr, ConfigDict
+from pydantic import RootModel, BaseModel, TypeAdapter, Field, AnyUrl, model_validator, PrivateAttr, ConfigDict
 
 from .json import JSONPointer, JSONReference
 from .errors import ReferenceResolutionError, OperationParameterValidationError
@@ -424,7 +424,7 @@ def get_type(
         discriminators: Optional[Sequence[DiscriminatorBase]] = None,
         extra: Optional["SchemaBase"] = None,
         fwdref: bool = False,
-    ) -> Union[Type[BaseModel], ForwardRef]:
+    ) -> Union[Type[BaseModel], Type[TypeAdapter], ForwardRef]:
         if fwdref:
             if "module" in ForwardRef.__init__.__code__.co_varnames:
                 # FIXME Python < 3.9 compat
@@ -449,18 +449,15 @@ def model(self, data: "JSON") -> Union[BaseModel, List[BaseModel]]:
         :rtype: self.get_type()
         """
 
-        if self.type == "boolean":
-            assert len(self.properties) == 0
-            t = Model.typeof(cast("SchemaType", self))
-            if not isinstance(data, t):
-                return t(data)
-            return data
+        type_ = cast("SchemaType", self.get_type())
+        if isinstance(type_, TypeAdapter):
+            r = type_.validate_python(data)
         else:
-            type_ = cast("SchemaType", self.get_type())
             r = type_.model_validate(data)
-            if self.type in ("string", "number", "integer", "array"):
+        if self.type in ("string", "number", "integer", "array", "boolean"):
+            if isinstance(r, RootModel):
                 return r.root
-            return r
+        return r
 
 
 class OperationBase:
diff --git a/aiopenapi3/model.py b/aiopenapi3/model.py
index b6f0dd79..1d25171e 100644
--- a/aiopenapi3/model.py
+++ b/aiopenapi3/model.py
@@ -17,7 +17,7 @@
     from typing import List, Optional, Union, Tuple, Dict
     from typing_extensions import Annotated, Literal
 
-from pydantic import BaseModel, Field, RootModel, ConfigDict
+from pydantic import BaseModel, TypeAdapter, Field, RootModel, ConfigDict
 import pydantic
 
 from .base import ReferenceBase, SchemaBase
@@ -69,12 +69,15 @@ def class_from_schema(s, _type):
     return b
 
 
+import pydantic_core
+
+
 @dataclasses.dataclass
 class _ClassInfo:
     @dataclasses.dataclass
     class _PropertyInfo:
         annotation: Any = None
-        default: Any = None
+        default: Any = pydantic_core.PydanticUndefined
 
     root: Any = None
     config: Dict[str, Any] = dataclasses.field(default_factory=dict)
@@ -115,16 +118,18 @@ def from_schema(
         schemanames: Optional[List[str]] = None,
         discriminators: Optional[List["DiscriminatorType"]] = None,
         extra: Optional["SchemaType"] = None,
-    ) -> Type[BaseModel]:
+    ) -> Union[Type[BaseModel], Type[TypeAdapter]]:
         if schemanames is None:
             schemanames = []
 
         if discriminators is None:
             discriminators = []
 
-        r: List[Type[BaseModel]] = list()
+        r: List[Union[Type[BaseModel], Type[TypeAdapter]]] = list()
 
         for _type in Model.types(schema):
+            if _type == "null":
+                continue
             r.append(Model.from_schema_type(schema, _type, schemanames, discriminators, extra))
 
         if len(r) > 1:
@@ -134,7 +139,13 @@ def from_schema(
         elif len(r) == 1:
             m: Type[BaseModel] = cast(Type[BaseModel], r[0])
         else:  # == 0
-            raise ValueError(r)
+            assert schema.type == "null"
+            return TypeAdapter(None.__class__)
+
+        if not isinstance(m, TypeAdapter) and Model.is_nullable(schema):
+            n = TypeAdapter(Optional[m])
+            return cast(Type[TypeAdapter], n)
+
         return cast(Type[BaseModel], m)
 
     @classmethod
@@ -152,11 +163,8 @@ def from_schema_type(
 
         classinfo = _ClassInfo()
 
-        # do not create models for primitive types
+        # create models for primitive types to be nullable
         if _type in ("string", "integer", "number", "boolean"):
-            if _type == "boolean":
-                return bool
-
             if typing.get_origin((_t := Model.typeof(schema, _type=_type))) != Literal:
                 classinfo.root = Annotated[_t, Model.fieldof_args(schema, None)]
             else:
@@ -325,7 +333,7 @@ def typeof(
         if schema is None:
             return BaseModel
         if isinstance(schema, SchemaBase):
-            nullable = False
+            nullable = Model.is_nullable(schema)
             schema = cast("SchemaType", schema)
             """
             Required, can be None: Optional[str]
@@ -520,7 +528,7 @@ def or_type(schema: "SchemaType", type_: str, l: Optional[int] = 2) -> bool:
 
     @staticmethod
     def is_nullable(schema: "SchemaType") -> bool:
-        return Model.or_type(schema, "null", l=None) or getattr(schema, "nullable", False)
+        return Model.or_type(schema, "null", l=None) or getattr(schema, "nullable", False) is True
 
     @staticmethod
     def is_type_any(schema: "SchemaType"):
@@ -537,14 +545,12 @@ def fieldof(schema: "SchemaType", classinfo: _ClassInfo):
             for name, f in schema.properties.items():
                 args: Dict[str, Any] = dict()
                 assert schema.required is not None
-                if name not in schema.required:
+                if (v := getattr(f, "default", None)) is not None:
+                    args["default"] = v
+                elif name not in schema.required:
                     args["default"] = None
+
                 name = Model.nameof(name, args=args)
-                if Model.is_nullable(f):
-                    args["default"] = None
-                for i in ["default"]:
-                    if (v := getattr(f, i, None)) is not None:
-                        args[i] = v
                 classinfo.properties[name].default = Model.fieldof_args(f, args)
         else:
             raise ValueError(schema.type)
diff --git a/tests/conftest.py b/tests/conftest.py
index 9c27ba05..e883b95b 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -493,3 +493,8 @@ def with_paths_response_error():
 @pytest.fixture
 def with_schema_ref_nesting():
     yield _get_parsed_yaml("schema-ref-nesting.yaml")
+
+
+@pytest.fixture
+def with_schema_nullable(openapi_version):
+    yield _get_parsed_yaml(f"schema-nullable-v{openapi_version.major}{openapi_version.minor}.yaml")
diff --git a/tests/fixtures/schema-nullable-v30.yaml b/tests/fixtures/schema-nullable-v30.yaml
new file mode 100644
index 00000000..fe9092e8
--- /dev/null
+++ b/tests/fixtures/schema-nullable-v30.yaml
@@ -0,0 +1,45 @@
+openapi: 3.0.3
+info:
+  title: ''
+  version: 0.0.0
+servers:
+  - url: http://127.0.0.1/api
+
+security:
+  - {}
+
+paths: {}
+
+components:
+  schemas:
+    object:
+      type: object
+      additionalProperties: false
+      properties:
+        attr:
+          $ref: '#/components/schemas/nullable'
+      nullable: true
+      required:
+      - attr
+
+    array:
+      type: array
+      items:
+        $ref: '#/components/schemas/nullable'
+      nullable: true
+
+    string:
+      type: string
+      nullable: true
+
+    integer:
+      type: integer
+      nullable: true
+
+    boolean:
+      type: boolean
+      nullable: true
+
+    nullable:
+      nullable: true
+      type: string
diff --git a/tests/fixtures/schema-nullable-v31.yaml b/tests/fixtures/schema-nullable-v31.yaml
new file mode 100644
index 00000000..37dd6933
--- /dev/null
+++ b/tests/fixtures/schema-nullable-v31.yaml
@@ -0,0 +1,40 @@
+openapi: 3.1.0
+info:
+  title: ''
+  version: 0.0.0
+servers:
+  - url: http://127.0.0.1/api
+
+security:
+  - {}
+
+paths: {}
+
+components:
+  schemas:
+    object:
+      type: [object, "null"]
+      additionalProperties: false
+      properties:
+        attr:
+          $ref: '#/components/schemas/nullable'
+      required:
+      - attr
+
+    array:
+      type: [array, "null"]
+      items:
+        $ref: '#/components/schemas/nullable'
+
+
+    string:
+      type: [string, "null"]
+
+    integer:
+      type: [integer, "null"]
+
+    boolean:
+      type: [boolean, "null"]
+
+    nullable:
+      type: [string, "null"]
diff --git a/tests/schema_test.py b/tests/schema_test.py
index f24843fe..581f1d95 100644
--- a/tests/schema_test.py
+++ b/tests/schema_test.py
@@ -423,11 +423,11 @@ def test_schema_enum(with_schema_enum):
     with pytest.raises(ValidationError):
         String(None)
 
-    Nullable = api.components.schemas["Nullable"].get_type()
-    Nullable("a")
-    Nullable(None)
+    Nullable = api.components.schemas["Nullable"]
+    Nullable.model("a")
+    Nullable.model(None)
     with pytest.raises(ValidationError):
-        Nullable("c")
+        Nullable.model("c")
 
     Mixed = api.components.schemas["Mixed"].get_type()
     Mixed(1)
@@ -470,3 +470,32 @@ def test_schema_baseurl_v20(with_schema_baseurl_v20):
 def test_schema_ref_nesting(with_schema_ref_nesting):
     for i in range(10):
         OpenAPI("/", with_schema_ref_nesting)
+
+
+@pytest.mark.parametrize(
+    "schema, input, output, okay",
+    [
+        ("object", None, None, True),
+        ("object", {"attr": "a"}, {"attr": "a"}, True),
+        ("object", {"attr": None}, {"attr": None}, True),
+        ("object", {}, {}, False),
+        ("integer", None, None, True),
+        ("integer", 1, 1, True),
+        ("boolean", None, None, True),
+        ("boolean", True, True, True),
+        ("string", None, None, True),
+        ("string", "a", "a", True),
+        ("array", None, None, True),
+        ("array", [], [], True),
+    ],
+)
+def test_schema_nullable(with_schema_nullable, schema, input, output, okay):
+    api = OpenAPI("/", with_schema_nullable)  # , plugins=[NullableRefs()])
+
+    m = api.components.schemas[schema]
+    t = m.get_type()
+    if okay:
+        m.model(input)
+    else:
+        with pytest.raises(ValidationError):
+            m.model(input)