diff --git a/openapi_core/shortcuts.py b/openapi_core/shortcuts.py
index 50c60103..00717ffa 100644
--- a/openapi_core/shortcuts.py
+++ b/openapi_core/shortcuts.py
@@ -5,15 +5,17 @@
 from typing import Union
 
 from jsonschema_path import SchemaPath
+from openapi_spec_validator.versions import consts as versions
+from openapi_spec_validator.versions.datatypes import SpecVersion
+from openapi_spec_validator.versions.exceptions import OpenAPIVersionNotFound
+from openapi_spec_validator.versions.shortcuts import get_spec_version
 
 from openapi_core.exceptions import SpecError
-from openapi_core.finders import SpecClasses
-from openapi_core.finders import SpecFinder
-from openapi_core.finders import SpecVersion
 from openapi_core.protocols import Request
 from openapi_core.protocols import Response
 from openapi_core.protocols import WebhookRequest
 from openapi_core.spec import Spec
+from openapi_core.types import SpecClasses
 from openapi_core.unmarshalling.request import V30RequestUnmarshaller
 from openapi_core.unmarshalling.request import V31RequestUnmarshaller
 from openapi_core.unmarshalling.request import V31WebhookRequestUnmarshaller
@@ -63,8 +65,8 @@
 
 AnyRequest = Union[Request, WebhookRequest]
 
-SPECS: Dict[SpecVersion, SpecClasses] = {
-    SpecVersion("openapi", "3.0"): SpecClasses(
+SPEC2CLASSES: Dict[SpecVersion, SpecClasses] = {
+    versions.OPENAPIV30: SpecClasses(
         V30RequestValidator,
         V30ResponseValidator,
         None,
@@ -74,7 +76,7 @@
         None,
         None,
     ),
-    SpecVersion("openapi", "3.1"): SpecClasses(
+    versions.OPENAPIV31: SpecClasses(
         V31RequestValidator,
         V31ResponseValidator,
         V31WebhookRequestValidator,
@@ -88,7 +90,15 @@
 
 
 def get_classes(spec: SchemaPath) -> SpecClasses:
-    return SpecFinder(SPECS).get_classes(spec)
+    try:
+        spec_version = get_spec_version(spec.contents())
+    # backward compatibility
+    except OpenAPIVersionNotFound:
+        raise SpecError("Spec schema version not detected")
+    try:
+        return SPEC2CLASSES[spec_version]
+    except KeyError:
+        raise SpecError("Spec schema version not supported")
 
 
 def unmarshal_apicall_request(
diff --git a/openapi_core/finders.py b/openapi_core/types.py
similarity index 74%
rename from openapi_core/finders.py
rename to openapi_core/types.py
index 3cb87b5c..9d9b1bc8 100644
--- a/openapi_core/finders.py
+++ b/openapi_core/types.py
@@ -1,3 +1,4 @@
+from dataclasses import dataclass
 from typing import Mapping
 from typing import NamedTuple
 from typing import Optional
@@ -21,12 +22,8 @@
 from openapi_core.validation.validators import BaseValidator
 
 
-class SpecVersion(NamedTuple):
-    name: str
-    version: str
-
-
-class SpecClasses(NamedTuple):
+@dataclass
+class SpecClasses:
     request_validator_cls: RequestValidatorType
     response_validator_cls: ResponseValidatorType
     webhook_request_validator_cls: Optional[WebhookRequestValidatorType]
@@ -37,14 +34,3 @@ class SpecClasses(NamedTuple):
     webhook_response_unmarshaller_cls: Optional[
         WebhookResponseUnmarshallerType
     ]
-
-
-class SpecFinder:
-    def __init__(self, specs: Mapping[SpecVersion, SpecClasses]) -> None:
-        self.specs = specs
-
-    def get_classes(self, spec: SchemaPath) -> SpecClasses:
-        for v, classes in self.specs.items():
-            if v.name in spec and spec[v.name].startswith(v.version):
-                return classes
-        raise SpecError("Spec schema version not detected")
diff --git a/tests/unit/conftest.py b/tests/unit/conftest.py
index 736eb9ab..63fad9df 100644
--- a/tests/unit/conftest.py
+++ b/tests/unit/conftest.py
@@ -2,6 +2,11 @@
 from jsonschema_path import SchemaPath
 
 
+@pytest.fixture
+def spec_v20():
+    return SchemaPath.from_dict({"swagger": "2.0"})
+
+
 @pytest.fixture
 def spec_v30():
     return SchemaPath.from_dict({"openapi": "3.0.0"})
diff --git a/tests/unit/test_shortcuts.py b/tests/unit/test_shortcuts.py
index 170c4cbf..1d83c569 100644
--- a/tests/unit/test_shortcuts.py
+++ b/tests/unit/test_shortcuts.py
@@ -97,6 +97,12 @@ def test_spec_not_detected(self, spec_invalid):
         with pytest.raises(SpecError):
             unmarshal_apicall_request(request, spec=spec_invalid)
 
+    def test_spec_not_supported(self, spec_v20):
+        request = mock.Mock(spec=Request)
+
+        with pytest.raises(SpecError):
+            unmarshal_apicall_request(request, spec=spec_v20)
+
     def test_request_type_invalid(self, spec_v31):
         request = mock.sentinel.request
 
@@ -124,6 +130,12 @@ def test_spec_not_detected(self, spec_invalid):
         with pytest.raises(SpecError):
             unmarshal_webhook_request(request, spec=spec_invalid)
 
+    def test_spec_not_supported(self, spec_v20):
+        request = mock.Mock(spec=WebhookRequest)
+
+        with pytest.raises(SpecError):
+            unmarshal_webhook_request(request, spec=spec_v20)
+
     def test_request_type_invalid(self, spec_v31):
         request = mock.sentinel.request
 
@@ -169,6 +181,12 @@ def test_spec_not_detected(self, spec_invalid):
         with pytest.raises(SpecError):
             unmarshal_request(request, spec=spec_invalid)
 
+    def test_spec_not_supported(self, spec_v20):
+        request = mock.Mock(spec=Request)
+
+        with pytest.raises(SpecError):
+            unmarshal_request(request, spec=spec_v20)
+
     def test_request_type_invalid(self, spec_v31):
         request = mock.sentinel.request
 
@@ -257,6 +275,13 @@ def test_spec_not_detected(self, spec_invalid):
         with pytest.raises(SpecError):
             unmarshal_apicall_response(request, response, spec=spec_invalid)
 
+    def test_spec_not_supported(self, spec_v20):
+        request = mock.Mock(spec=Request)
+        response = mock.Mock(spec=Response)
+
+        with pytest.raises(SpecError):
+            unmarshal_apicall_response(request, response, spec=spec_v20)
+
     def test_request_type_invalid(self, spec_v31):
         request = mock.sentinel.request
         response = mock.Mock(spec=Response)
@@ -297,6 +322,13 @@ def test_spec_not_detected(self, spec_invalid):
         with pytest.raises(SpecError):
             unmarshal_response(request, response, spec=spec_invalid)
 
+    def test_spec_not_supported(self, spec_v20):
+        request = mock.Mock(spec=Request)
+        response = mock.Mock(spec=Response)
+
+        with pytest.raises(SpecError):
+            unmarshal_response(request, response, spec=spec_v20)
+
     def test_request_type_invalid(self, spec_v31):
         request = mock.sentinel.request
         response = mock.Mock(spec=Response)
@@ -404,6 +436,13 @@ def test_spec_not_detected(self, spec_invalid):
         with pytest.raises(SpecError):
             unmarshal_webhook_response(request, response, spec=spec_invalid)
 
+    def test_spec_not_supported(self, spec_v20):
+        request = mock.Mock(spec=WebhookRequest)
+        response = mock.Mock(spec=Response)
+
+        with pytest.raises(SpecError):
+            unmarshal_webhook_response(request, response, spec=spec_v20)
+
     def test_request_type_invalid(self, spec_v31):
         request = mock.sentinel.request
         response = mock.Mock(spec=Response)
@@ -463,6 +502,12 @@ def test_spec_not_detected(self, spec_invalid):
         with pytest.raises(SpecError):
             validate_apicall_request(request, spec=spec_invalid)
 
+    def test_spec_not_supported(self, spec_v20):
+        request = mock.Mock(spec=Request)
+
+        with pytest.raises(SpecError):
+            validate_apicall_request(request, spec=spec_v20)
+
     def test_request_type_invalid(self, spec_v31):
         request = mock.sentinel.request
 
@@ -502,6 +547,12 @@ def test_spec_not_detected(self, spec_invalid):
         with pytest.raises(SpecError):
             validate_webhook_request(request, spec=spec_invalid)
 
+    def test_spec_not_supported(self, spec_v20):
+        request = mock.Mock(spec=WebhookRequest)
+
+        with pytest.raises(SpecError):
+            validate_webhook_request(request, spec=spec_v20)
+
     def test_request_type_invalid(self, spec_v31):
         request = mock.sentinel.request
 
@@ -548,6 +599,13 @@ def test_spec_not_detected(self, spec_invalid):
             with pytest.warns(DeprecationWarning):
                 validate_request(request, spec=spec_invalid)
 
+    def test_spec_not_detected(self, spec_v20):
+        request = mock.Mock(spec=Request)
+
+        with pytest.raises(SpecError):
+            with pytest.warns(DeprecationWarning):
+                validate_request(request, spec=spec_v20)
+
     def test_request_type_invalid(self, spec_v31):
         request = mock.sentinel.request
 
@@ -705,6 +763,13 @@ def test_spec_not_detected(self, spec_invalid):
         with pytest.raises(SpecError):
             validate_apicall_response(request, response, spec=spec_invalid)
 
+    def test_spec_not_supported(self, spec_v20):
+        request = mock.Mock(spec=Request)
+        response = mock.Mock(spec=Response)
+
+        with pytest.raises(SpecError):
+            validate_apicall_response(request, response, spec=spec_v20)
+
     def test_request_type_invalid(self, spec_v31):
         request = mock.sentinel.request
         response = mock.Mock(spec=Response)
@@ -758,6 +823,13 @@ def test_spec_not_detected(self, spec_invalid):
         with pytest.raises(SpecError):
             validate_webhook_response(request, response, spec=spec_invalid)
 
+    def test_spec_not_supported(self, spec_v20):
+        request = mock.Mock(spec=WebhookRequest)
+        response = mock.Mock(spec=Response)
+
+        with pytest.raises(SpecError):
+            validate_webhook_response(request, response, spec=spec_v20)
+
     def test_request_type_invalid(self, spec_v31):
         request = mock.sentinel.request
         response = mock.Mock(spec=Response)
@@ -819,6 +891,14 @@ def test_spec_not_detected(self, spec_invalid):
             with pytest.warns(DeprecationWarning):
                 validate_response(request, response, spec=spec_invalid)
 
+    def test_spec_not_supported(self, spec_v20):
+        request = mock.Mock(spec=Request)
+        response = mock.Mock(spec=Response)
+
+        with pytest.raises(SpecError):
+            with pytest.warns(DeprecationWarning):
+                validate_response(request, response, spec=spec_v20)
+
     def test_request_type_invalid(self, spec_v31):
         request = mock.sentinel.request
         response = mock.Mock(spec=Response)