diff --git a/ChangeLog b/ChangeLog
index 490768ecaa..3d663b05ea 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+Sun Jan  3 23:55:13 2016  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* lib/rubygems/security.rb (DIGEST_ALGORITHM, KEY_ALGORITHM):
+	  should check same name as the used constants.
+	  [ruby-core:72674] [Bug #11940]
+
 Sun Jan  3 19:22:01 2016  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* aclocal.m4: add fallback file for non-aclocal environments.
diff --git a/lib/rubygems/security.rb b/lib/rubygems/security.rb
index d44ebec9f5..941462d7bd 100644
--- a/lib/rubygems/security.rb
+++ b/lib/rubygems/security.rb
@@ -340,7 +340,7 @@ module Gem::Security
   # Digest algorithm used to sign gems
 
   DIGEST_ALGORITHM =
-    if defined?(OpenSSL::Digest) then
+    if defined?(OpenSSL::Digest::SHA1) then
       OpenSSL::Digest::SHA1
     end
 
@@ -356,7 +356,7 @@ module Gem::Security
   # Algorithm for creating the key pair used to sign gems
 
   KEY_ALGORITHM =
-    if defined?(OpenSSL::PKey) then
+    if defined?(OpenSSL::PKey::RSA) then
       OpenSSL::PKey::RSA
     end