diff --git a/openapi_core/schema/schemas/enums.py b/openapi_core/schema/schemas/enums.py
index 8b77e7c..3cfe035 100644
--- a/openapi_core/schema/schemas/enums.py
+++ b/openapi_core/schema/schemas/enums.py
@@ -26,3 +26,8 @@ class SchemaFormat(Enum):
     DATETIME = 'date-time'
     PASSWORD = 'password'
     UUID = 'uuid'
+
+
+class UnmarshalContext(Enum):
+    REQUEST = 'request'
+    RESPONSE = 'response'
diff --git a/openapi_core/validation/request/validators.py b/openapi_core/validation/request/validators.py
index ccfe380..df07e05 100644
--- a/openapi_core/validation/request/validators.py
+++ b/openapi_core/validation/request/validators.py
@@ -11,6 +11,7 @@ from openapi_core.schema.parameters.exceptions import (
 )
 from openapi_core.schema.paths.exceptions import InvalidPath
 from openapi_core.schema.request_bodies.exceptions import MissingRequestBody
+from openapi_core.schema.schemas.enums import UnmarshalContext
 from openapi_core.schema.servers.exceptions import InvalidServer
 from openapi_core.security.exceptions import SecurityError
 from openapi_core.unmarshalling.schemas.exceptions import (
@@ -23,6 +24,8 @@ from openapi_core.validation.request.datatypes import (
 from openapi_core.validation.util import get_operation_pattern
 
 
+_CONTEXT = UnmarshalContext.REQUEST
+
 class RequestValidator(object):
 
     def __init__(
diff --git a/openapi_core/validation/response/validators.py b/openapi_core/validation/response/validators.py
index 241e8d9..8e93057 100644
--- a/openapi_core/validation/response/validators.py
+++ b/openapi_core/validation/response/validators.py
@@ -6,6 +6,7 @@ from openapi_core.schema.media_types.exceptions import InvalidContentType
 from openapi_core.schema.responses.exceptions import (
     InvalidResponse, MissingResponseContent,
 )
+from openapi_core.schema.schemas.enums import UnmarshalContext
 from openapi_core.schema.servers.exceptions import InvalidServer
 from openapi_core.unmarshalling.schemas.exceptions import (
     UnmarshalError, ValidateError,
@@ -13,6 +14,8 @@ from openapi_core.unmarshalling.schemas.exceptions import (
 from openapi_core.validation.response.datatypes import ResponseValidationResult
 from openapi_core.validation.util import get_operation_pattern
 
+_CONTEXT = UnmarshalContext.RESPONSE
+
 
 class ResponseValidator(object):
 
@@ -73,6 +76,7 @@ class ResponseValidator(object):
 
         try:
             media_type = operation_response[response.mimetype]
+
         except InvalidContentType as exc:
             return None, [exc, ]