diff --git a/ChangeLog b/ChangeLog
index cbecfc2365..23c978f1a9 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Mon Jan  2 20:53:36 2012  Tanaka Akira  <akr@fsij.org>
+
+	* lib/securerandom.rb (random_bytes): use IO#read instead of
+	  IO#readpartial to make the intent more clear.
+
 Mon Jan  2 15:26:39 2012  Kazuki Tsujimoto  <kazuki@callcc.net>
 
 	* test/ruby/test_object.rb (test_send_with_block): add a normal case.
diff --git a/lib/securerandom.rb b/lib/securerandom.rb
index 04e8bc205e..eede2fef04 100644
--- a/lib/securerandom.rb
+++ b/lib/securerandom.rb
@@ -78,7 +78,7 @@ module SecureRandom
             raise Errno::ENOENT
           end
           @has_urandom = true
-          ret = f.readpartial(n)
+          ret = f.read(n)
           if ret.length != n
             raise NotImplementedError, "Unexpected partial read from random device"
           end