diff --git a/ChangeLog b/ChangeLog
index 3f7ab2004f..8faa7ff363 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Fri Apr 25 12:51:08 2014  NARUSE, Yui  <naruse@ruby-lang.org>
+
+	* configure.in: correct pthread_setname_np's prototype on NetBSD.
+	  [Bug #9586]
+
 Thu Apr 24 23:17:25 2014  NAKAMURA Usaku  <usa@ruby-lang.org>
 
 	* lib/fileutils.rb (fu_get_uid, fu_get_gid): Etc.getpwnam/getgrnam may
diff --git a/configure.in b/configure.in
index 8a9254d738..93c01631ad 100644
--- a/configure.in
+++ b/configure.in
@@ -2546,9 +2546,12 @@ if test x"$enable_pthread" = xyes; then
     if test "$ac_cv_func_pthread_setname_np" = yes; then
 	AC_CACHE_CHECK([arguments of pthread_setname_np], [rb_cv_func_pthread_setname_np_arguments],
 	    [rb_cv_func_pthread_setname_np_arguments=
+	    # Linux,AIX,  (pthread_self(), name)
+	    # NetBSD (pthread_self(), name, \"%s\")
+	    # Darwin (name)
 	    for mac in \
 		"(pthread_self(), name)" \
-		"(pthread_self(), "%s", name)" \
+		"(pthread_self(), name, \"%s\")" \
 		"(name)" \
 		; do
 		AC_TRY_COMPILE([