diff --git a/src/cryptography/x509/__init__.py b/src/cryptography/x509/__init__.py
index 0beff1f..8e345ae 100644
--- a/src/cryptography/x509/__init__.py
+++ b/src/cryptography/x509/__init__.py
@@ -5,21 +5,21 @@
 from __future__ import absolute_import, division, print_function
 
 from cryptography.x509.base import (
-    Certificate, CertificateBuilder,
-    CertificatePolicies, CertificateRevocationList, CertificateSigningRequest,
-    CertificateSigningRequestBuilder,
-    DuplicateExtension, ExtendedKeyUsage, Extension, ExtensionNotFound,
-    ExtensionType, Extensions, GeneralNames, InhibitAnyPolicy,
+    Certificate, CertificateBuilder, CertificateRevocationList,
+    CertificateSigningRequest, CertificateSigningRequestBuilder,
+    DuplicateExtension, Extension, ExtensionNotFound,
+    ExtensionType, Extensions, GeneralNames,
     InvalidVersion, IssuerAlternativeName, KeyUsage, NameConstraints,
-    NoticeReference, OCSPNoCheck, ObjectIdentifier,
-    PolicyInformation, RevokedCertificate, SubjectAlternativeName,
-    UnsupportedExtension, UserNotice, Version, load_der_x509_certificate,
+    ObjectIdentifier, RevokedCertificate, SubjectAlternativeName,
+    UnsupportedExtension, Version, load_der_x509_certificate,
     load_der_x509_csr, load_pem_x509_certificate, load_pem_x509_csr,
 )
 from cryptography.x509.extensions import (
     AccessDescription, AuthorityInformationAccess,
     AuthorityKeyIdentifier, BasicConstraints, CRLDistributionPoints,
-    DistributionPoint, ReasonFlags, SubjectKeyIdentifier
+    CertificatePolicies, DistributionPoint, ExtendedKeyUsage,
+    InhibitAnyPolicy, NoticeReference, OCSPNoCheck, PolicyInformation,
+    ReasonFlags, SubjectKeyIdentifier, UserNotice
 )
 from cryptography.x509.general_name import (
     DNSName, DirectoryName, GeneralName, IPAddress, OtherName, RFC822Name,
diff --git a/src/cryptography/x509/base.py b/src/cryptography/x509/base.py
index 7e755de..2b4eeb5 100644
--- a/src/cryptography/x509/base.py
+++ b/src/cryptography/x509/base.py
@@ -132,42 +132,6 @@
 
 
 @utils.register_interface(ExtensionType)
-class ExtendedKeyUsage(object):
-    oid = ExtensionOID.EXTENDED_KEY_USAGE
-
-    def __init__(self, usages):
-        if not all(isinstance(x, ObjectIdentifier) for x in usages):
-            raise TypeError(
-                "Every item in the usages list must be an ObjectIdentifier"
-            )
-
-        self._usages = usages
-
-    def __iter__(self):
-        return iter(self._usages)
-
-    def __len__(self):
-        return len(self._usages)
-
-    def __repr__(self):
-        return "<ExtendedKeyUsage({0})>".format(self._usages)
-
-    def __eq__(self, other):
-        if not isinstance(other, ExtendedKeyUsage):
-            return NotImplemented
-
-        return self._usages == other._usages
-
-    def __ne__(self, other):
-        return not self == other
-
-
-@utils.register_interface(ExtensionType)
-class OCSPNoCheck(object):
-    oid = ExtensionOID.OCSP_NO_CHECK
-
-
-@utils.register_interface(ExtensionType)
 class KeyUsage(object):
     oid = ExtensionOID.KEY_USAGE
 
@@ -254,146 +218,6 @@
 
 
 @utils.register_interface(ExtensionType)
-class CertificatePolicies(object):
-    oid = ExtensionOID.CERTIFICATE_POLICIES
-
-    def __init__(self, policies):
-        if not all(isinstance(x, PolicyInformation) for x in policies):
-            raise TypeError(
-                "Every item in the policies list must be a "
-                "PolicyInformation"
-            )
-
-        self._policies = policies
-
-    def __iter__(self):
-        return iter(self._policies)
-
-    def __len__(self):
-        return len(self._policies)
-
-    def __repr__(self):
-        return "<CertificatePolicies({0})>".format(self._policies)
-
-    def __eq__(self, other):
-        if not isinstance(other, CertificatePolicies):
-            return NotImplemented
-
-        return self._policies == other._policies
-
-    def __ne__(self, other):
-        return not self == other
-
-
-class PolicyInformation(object):
-    def __init__(self, policy_identifier, policy_qualifiers):
-        if not isinstance(policy_identifier, ObjectIdentifier):
-            raise TypeError("policy_identifier must be an ObjectIdentifier")
-
-        self._policy_identifier = policy_identifier
-        if policy_qualifiers and not all(
-            isinstance(
-                x, (six.text_type, UserNotice)
-            ) for x in policy_qualifiers
-        ):
-            raise TypeError(
-                "policy_qualifiers must be a list of strings and/or UserNotice"
-                " objects or None"
-            )
-
-        self._policy_qualifiers = policy_qualifiers
-
-    def __repr__(self):
-        return (
-            "<PolicyInformation(policy_identifier={0.policy_identifier}, polic"
-            "y_qualifiers={0.policy_qualifiers})>".format(self)
-        )
-
-    def __eq__(self, other):
-        if not isinstance(other, PolicyInformation):
-            return NotImplemented
-
-        return (
-            self.policy_identifier == other.policy_identifier and
-            self.policy_qualifiers == other.policy_qualifiers
-        )
-
-    def __ne__(self, other):
-        return not self == other
-
-    policy_identifier = utils.read_only_property("_policy_identifier")
-    policy_qualifiers = utils.read_only_property("_policy_qualifiers")
-
-
-class UserNotice(object):
-    def __init__(self, notice_reference, explicit_text):
-        if notice_reference and not isinstance(
-            notice_reference, NoticeReference
-        ):
-            raise TypeError(
-                "notice_reference must be None or a NoticeReference"
-            )
-
-        self._notice_reference = notice_reference
-        self._explicit_text = explicit_text
-
-    def __repr__(self):
-        return (
-            "<UserNotice(notice_reference={0.notice_reference}, explicit_text="
-            "{0.explicit_text!r})>".format(self)
-        )
-
-    def __eq__(self, other):
-        if not isinstance(other, UserNotice):
-            return NotImplemented
-
-        return (
-            self.notice_reference == other.notice_reference and
-            self.explicit_text == other.explicit_text
-        )
-
-    def __ne__(self, other):
-        return not self == other
-
-    notice_reference = utils.read_only_property("_notice_reference")
-    explicit_text = utils.read_only_property("_explicit_text")
-
-
-class NoticeReference(object):
-    def __init__(self, organization, notice_numbers):
-        self._organization = organization
-        if not isinstance(notice_numbers, list) or not all(
-            isinstance(x, int) for x in notice_numbers
-        ):
-            raise TypeError(
-                "notice_numbers must be a list of integers"
-            )
-
-        self._notice_numbers = notice_numbers
-
-    def __repr__(self):
-        return (
-            "<NoticeReference(organization={0.organization!r}, notice_numbers="
-            "{0.notice_numbers})>".format(self)
-        )
-
-    def __eq__(self, other):
-        if not isinstance(other, NoticeReference):
-            return NotImplemented
-
-        return (
-            self.organization == other.organization and
-            self.notice_numbers == other.notice_numbers
-        )
-
-    def __ne__(self, other):
-        return not self == other
-
-    organization = utils.read_only_property("_organization")
-    notice_numbers = utils.read_only_property("_notice_numbers")
-
-
-@utils.register_interface(ExtensionType)
 class NameConstraints(object):
     oid = ExtensionOID.NAME_CONSTRAINTS
 
@@ -460,34 +284,6 @@
     excluded_subtrees = utils.read_only_property("_excluded_subtrees")
 
 
-@utils.register_interface(ExtensionType)
-class InhibitAnyPolicy(object):
-    oid = ExtensionOID.INHIBIT_ANY_POLICY
-
-    def __init__(self, skip_certs):
-        if not isinstance(skip_certs, six.integer_types):
-            raise TypeError("skip_certs must be an integer")
-
-        if skip_certs < 0:
-            raise ValueError("skip_certs must be a non-negative integer")
-
-        self._skip_certs = skip_certs
-
-    def __repr__(self):
-        return "<InhibitAnyPolicy(skip_certs={0.skip_certs})>".format(self)
-
-    def __eq__(self, other):
-        if not isinstance(other, InhibitAnyPolicy):
-            return NotImplemented
-
-        return self.skip_certs == other.skip_certs
-
-    def __ne__(self, other):
-        return not self == other
-
-    skip_certs = utils.read_only_property("_skip_certs")
-
-
 class GeneralNames(object):
     def __init__(self, general_names):
         if not all(isinstance(x, GeneralName) for x in general_names):
diff --git a/src/cryptography/x509/extensions.py b/src/cryptography/x509/extensions.py
index eef9f11..f227dfe 100644
--- a/src/cryptography/x509/extensions.py
+++ b/src/cryptography/x509/extensions.py
@@ -18,7 +18,7 @@
 from cryptography.x509.general_name import GeneralName
 from cryptography.x509.name import Name
 from cryptography.x509.oid import (
-    AuthorityInformationAccessOID, ExtensionOID
+    AuthorityInformationAccessOID, ExtensionOID, ObjectIdentifier
 )
 
 
@@ -375,3 +375,207 @@
     privilege_withdrawn = "privilegeWithdrawn"
     aa_compromise = "aACompromise"
     remove_from_crl = "removeFromCRL"
+
+
+@utils.register_interface(ExtensionType)
+class CertificatePolicies(object):
+    oid = ExtensionOID.CERTIFICATE_POLICIES
+
+    def __init__(self, policies):
+        if not all(isinstance(x, PolicyInformation) for x in policies):
+            raise TypeError(
+                "Every item in the policies list must be a "
+                "PolicyInformation"
+            )
+
+        self._policies = policies
+
+    def __iter__(self):
+        return iter(self._policies)
+
+    def __len__(self):
+        return len(self._policies)
+
+    def __repr__(self):
+        return "<CertificatePolicies({0})>".format(self._policies)
+
+    def __eq__(self, other):
+        if not isinstance(other, CertificatePolicies):
+            return NotImplemented
+
+        return self._policies == other._policies
+
+    def __ne__(self, other):
+        return not self == other
+
+
+class PolicyInformation(object):
+    def __init__(self, policy_identifier, policy_qualifiers):
+        if not isinstance(policy_identifier, ObjectIdentifier):
+            raise TypeError("policy_identifier must be an ObjectIdentifier")
+
+        self._policy_identifier = policy_identifier
+        if policy_qualifiers and not all(
+            isinstance(
+                x, (six.text_type, UserNotice)
+            ) for x in policy_qualifiers
+        ):
+            raise TypeError(
+                "policy_qualifiers must be a list of strings and/or UserNotice"
+                " objects or None"
+            )
+
+        self._policy_qualifiers = policy_qualifiers
+
+    def __repr__(self):
+        return (
+            "<PolicyInformation(policy_identifier={0.policy_identifier}, polic"
+            "y_qualifiers={0.policy_qualifiers})>".format(self)
+        )
+
+    def __eq__(self, other):
+        if not isinstance(other, PolicyInformation):
+            return NotImplemented
+
+        return (
+            self.policy_identifier == other.policy_identifier and
+            self.policy_qualifiers == other.policy_qualifiers
+        )
+
+    def __ne__(self, other):
+        return not self == other
+
+    policy_identifier = utils.read_only_property("_policy_identifier")
+    policy_qualifiers = utils.read_only_property("_policy_qualifiers")
+
+
+class UserNotice(object):
+    def __init__(self, notice_reference, explicit_text):
+        if notice_reference and not isinstance(
+            notice_reference, NoticeReference
+        ):
+            raise TypeError(
+                "notice_reference must be None or a NoticeReference"
+            )
+
+        self._notice_reference = notice_reference
+        self._explicit_text = explicit_text
+
+    def __repr__(self):
+        return (
+            "<UserNotice(notice_reference={0.notice_reference}, explicit_text="
+            "{0.explicit_text!r})>".format(self)
+        )
+
+    def __eq__(self, other):
+        if not isinstance(other, UserNotice):
+            return NotImplemented
+
+        return (
+            self.notice_reference == other.notice_reference and
+            self.explicit_text == other.explicit_text
+        )
+
+    def __ne__(self, other):
+        return not self == other
+
+    notice_reference = utils.read_only_property("_notice_reference")
+    explicit_text = utils.read_only_property("_explicit_text")
+
+
+class NoticeReference(object):
+    def __init__(self, organization, notice_numbers):
+        self._organization = organization
+        if not isinstance(notice_numbers, list) or not all(
+            isinstance(x, int) for x in notice_numbers
+        ):
+            raise TypeError(
+                "notice_numbers must be a list of integers"
+            )
+
+        self._notice_numbers = notice_numbers
+
+    def __repr__(self):
+        return (
+            "<NoticeReference(organization={0.organization!r}, notice_numbers="
+            "{0.notice_numbers})>".format(self)
+        )
+
+    def __eq__(self, other):
+        if not isinstance(other, NoticeReference):
+            return NotImplemented
+
+        return (
+            self.organization == other.organization and
+            self.notice_numbers == other.notice_numbers
+        )
+
+    def __ne__(self, other):
+        return not self == other
+
+    organization = utils.read_only_property("_organization")
+    notice_numbers = utils.read_only_property("_notice_numbers")
+
+
+@utils.register_interface(ExtensionType)
+class ExtendedKeyUsage(object):
+    oid = ExtensionOID.EXTENDED_KEY_USAGE
+
+    def __init__(self, usages):
+        if not all(isinstance(x, ObjectIdentifier) for x in usages):
+            raise TypeError(
+                "Every item in the usages list must be an ObjectIdentifier"
+            )
+
+        self._usages = usages
+
+    def __iter__(self):
+        return iter(self._usages)
+
+    def __len__(self):
+        return len(self._usages)
+
+    def __repr__(self):
+        return "<ExtendedKeyUsage({0})>".format(self._usages)
+
+    def __eq__(self, other):
+        if not isinstance(other, ExtendedKeyUsage):
+            return NotImplemented
+
+        return self._usages == other._usages
+
+    def __ne__(self, other):
+        return not self == other
+
+
+@utils.register_interface(ExtensionType)
+class OCSPNoCheck(object):
+    oid = ExtensionOID.OCSP_NO_CHECK
+
+
+@utils.register_interface(ExtensionType)
+class InhibitAnyPolicy(object):
+    oid = ExtensionOID.INHIBIT_ANY_POLICY
+
+    def __init__(self, skip_certs):
+        if not isinstance(skip_certs, six.integer_types):
+            raise TypeError("skip_certs must be an integer")
+
+        if skip_certs < 0:
+            raise ValueError("skip_certs must be a non-negative integer")
+
+        self._skip_certs = skip_certs
+
+    def __repr__(self):
+        return "<InhibitAnyPolicy(skip_certs={0.skip_certs})>".format(self)
+
+    def __eq__(self, other):
+        if not isinstance(other, InhibitAnyPolicy):
+            return NotImplemented
+
+        return self.skip_certs == other.skip_certs
+
+    def __ne__(self, other):
+        return not self == other
+
+    skip_certs = utils.read_only_property("_skip_certs")