diff --git a/ChangeLog b/ChangeLog
index 8da6cac116..73fbb1491f 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Wed Dec  2 15:12:43 2015  SHIBATA Hiroshi  <hsbt@ruby-lang.org>
+
+	* configure.in: Fixed double negative comments.
+	  [Bug #11698][ruby-core:71506]
+
 Wed Dec  2 14:55:01 2015  yui-knk  <spiketeika@gmail.com>
 
 	* test/ruby/test_string.rb: removed non executing tests.
diff --git a/configure.in b/configure.in
index 0f42782f55..24014c0597 100644
--- a/configure.in
+++ b/configure.in
@@ -3837,7 +3837,7 @@ dnl build rdoc index if requested
 RDOCTARGET=""
 CAPITARGET=""
 AC_ARG_ENABLE(install-doc,
-       AS_HELP_STRING([--disable-install-doc], [do not install neither rdoc indexes nor C API documents during install]),
+       AS_HELP_STRING([--disable-install-doc], [do not install either rdoc indexes or C API documents during install]),
        [install_doc=$enableval], [install_doc=yes])
 AC_ARG_ENABLE(install-rdoc,
       AS_HELP_STRING([--disable-install-rdoc], [do not install rdoc indexes during install]),