diff --git a/ChangeLog b/ChangeLog
index 4a735a6858..25cedeee06 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+Wed Apr  6 10:56:15 2016  Anton Davydov  <antondavydov.o@gmail.com>
+
+	* lib/logger.rb (Logger#level=): remove unnecessary local
+	  variable.
+
+	* lib/logger.rb (Logger#initialize, Logger#reopen): [DOC] mention
+	  the default values.  cherrypicked from [GH-1319].
+
 Wed Apr  6 10:17:53 2016  cremno phobia  <cremno@mail.ru>
 
 	* math.c (ruby_lgamma_r): missing/lgamma_r.c is used on Windows,
diff --git a/lib/logger.rb b/lib/logger.rb
index 8393806a11..f3a29fa47d 100644
--- a/lib/logger.rb
+++ b/lib/logger.rb
@@ -251,8 +251,7 @@ class Logger
     if severity.is_a?(Integer)
       @level = severity
     else
-      _severity = severity.to_s.downcase
-      case _severity
+      case severity.to_s.downcase
       when 'debug'.freeze
         @level = DEBUG
       when 'info'.freeze
@@ -335,9 +334,10 @@ class Logger
   #   +STDOUT+, +STDERR+, or an open file).
   # +shift_age+::
   #   Number of old log files to keep, *or* frequency of rotation (+daily+,
-  #   +weekly+ or +monthly+).
+  #   +weekly+ or +monthly+). Default value is 0.
   # +shift_size+::
-  #   Maximum logfile size (only applies when +shift_age+ is a number).
+  #   Maximum logfile size (only applies when +shift_age+ is a number). Default
+  #   value is 1MiB.
   #
   # === Description
   #
@@ -364,7 +364,8 @@ class Logger
   #
   # +logdev+::
   #   The log device.  This is a filename (String) or IO object (typically
-  #   +STDOUT+, +STDERR+, or an open file).
+  #   +STDOUT+, +STDERR+, or an open file).  reopen the same filename if
+  #   it is +nil+, do nothing for IO.  Default is +nil+.
   #
   # === Description
   #