diff --git a/ext/openssl/ossl.c b/ext/openssl/ossl.c
index f3410b6..f964518 100644
--- a/ext/openssl/ossl.c
+++ b/ext/openssl/ossl.c
@@ -560,24 +560,29 @@ ossl_debug_set(VALUE self, VALUE val)
  *   cert.public_key = key.public_key
  *   cert.subject = name
  *
  * === Certificate Extensions
  *
  * You can add extensions to the certificate with
  * OpenSSL::SSL::ExtensionFactory to indicate the purpose of the certificate.
  *
  *   extension_factory = OpenSSL::X509::ExtensionFactory.new nil, cert
  *
- *   extension_factory.create_extension 'basicConstraints', 'CA:FALSE'
- *   extension_factory.create_extension 'keyUsage',
- *     'keyEncipherment,dataEncipherment,digitalSignature'
- *   extension_factory.create_extension 'subjectKeyIdentifier', 'hash'
+ *   cert.add_extension(extension_factory.create_extension
+ *     'basicConstraints', 'CA:FALSE')
+ *   cert.add_extension(extension_factory.create_extension
+ *     'keyUsage', 'keyEncipherment,dataEncipherment,digitalSignature')
+ *   cert.add_extension(extension_factory.create_extension
+ *     'subjectKeyIdentifier', 'hash')
+ *
+ * The list of supported extensions (and in some cases their possible values)
+ * can be derived from the "objects.h" file in the OpenSSL source code.
  *
  * === Signing a Certificate
  *
  * To sign a certificate set the issuer and use OpenSSL::X509::Certificate#sign
  * with a digest algorithm.  This creates a self-signed cert because we're using
  * the same name and key to sign the certificate as was used to create the
  * certificate.
  *
  *   cert.issuer = name
  *   cert.sign key, OpenSSL::Digest::SHA1.new
@@ -631,30 +636,33 @@ ossl_debug_set(VALUE self, VALUE val)
  *   ca_cert.not_after = Time.now + 86400
  *
  *   ca_cert.public_key = ca_key.public_key
  *   ca_cert.subject = ca_name
  *   ca_cert.issuer = ca_name
  *
  *   extension_factory = OpenSSL::X509::ExtensionFactory.new
  *   extension_factory.subject_certificate = ca_cert
  *   extension_factory.issuer_certificate = ca_cert
  *
- *   extension_factory.create_extension 'subjectKeyIdentifier', 'hash'
+ *   ca_cert.add_extension(extension_factory.create_extension
+ *     'subjectKeyIdentifier', 'hash'
  *
  * This extension indicates the CA's key may be used as a CA.
  *
- *   extension_factory.create_extension 'basicConstraints', 'CA:TRUE', true
+ *   ca_cert.add_extension(extension_factory.create_extension
+ *     'basicConstraints', 'CA:TRUE', true
  *
  * This extension indicates the CA's key may be used to verify signatures on
  * both certificates and certificate revocations.
  *
- *   extension_factory.create_extension 'keyUsage', 'cRLSign,keyCertSign', true
+ *   ca_cert.add_extension(extension_factory.create_extension
+ *     'keyUsage', 'cRLSign,keyCertSign', true
  *
  * Root CA certificates are self-signed.
  *
  *   ca_cert.sign ca_key, OpenSSL::Digest::SHA1.new
  *
  * The CA certificate is saved to disk so it may be distributed to all the
  * users of the keys this CA will sign.
  *
  *   open 'ca_cert.pem', 'w' do |io|
  *     io.write ca_cert.to_pem
@@ -696,24 +704,26 @@ ossl_debug_set(VALUE self, VALUE val)
  *   csr_cert.not_after = Time.now + 600
  *
  *   csr_cert.subject = csr.subject
  *   csr_cert.public_key = csr.public_key
  *   csr_cert.issuer = ca_cert.subject
  *
  *   extension_factory = OpenSSL::X509::ExtensionFactory.new
  *   extension_factory.subject_certificate = csr_cert
  *   extension_factory.issuer_certificate = ca_cert
  *
- *   extension_factory.create_extension 'basicConstraints', 'CA:FALSE'
- *   extension_factory.create_extension 'keyUsage',
- *     'keyEncipherment,dataEncipherment,digitalSignature'
- *   extension_factory.create_extension 'subjectKeyIdentifier', 'hash'
+ *   csr_cert.add_extension(extension_factory.create_extension
+ *     'basicConstraints', 'CA:FALSE')
+ *   csr_cert.add_extension(extension_factory.create_extension
+ *     'keyUsage', 'keyEncipherment,dataEncipherment,digitalSignature')
+ *   csr_cert.add_extension(extension_factory.create_extension
+ *     'subjectKeyIdentifier', 'hash')
  *
  *   csr_cert.sign ca_key, OpenSSL::Digest::SHA1.new
  *
  *   open 'csr_cert.pem', 'w' do |io|
  *     io.write csr_cert.to_pem
  *   end
  *
  * == SSL and TLS Connections
  *
  * Using our created key and certificate we can create an SSL or TLS connection.