diff --git a/ChangeLog b/ChangeLog
index a4b2b0411a..b7fae5aae2 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+Sat Oct 22 10:27:01 2016  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* configure.in (RUBY_APPEND_OPTION, RUBY_PREPEND_OPTION): expand
+	  the option to be appended/prepended when matching, as well as
+	  RUBY_APPEND_OPTIONS and  RUBY_PREPEND_OPTIONS.
+
 Sat Oct 22 09:52:57 2016  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* compile.c (setup_args): duplicate splatting array if more
diff --git a/configure.in b/configure.in
index 8dd3aa9e66..9d355e1250 100644
--- a/configure.in
+++ b/configure.in
@@ -311,7 +311,7 @@ AS_IF([test -z "$target_alias" -a -n "$os_version_style_transform"],
 AC_DEFUN([RUBY_APPEND_OPTION],
 	[# RUBY_APPEND_OPTION($1)
 	AS_CASE([" [$]{$1-} "],
-	[*' $2 '*], [], ['  '], [ $1="$2"], [ $1="[$]$1 $2"])])
+	[*" $2 "*], [], ['  '], [ $1="$2"], [ $1="[$]$1 $2"])])
 AC_DEFUN([RUBY_APPEND_OPTIONS],
 	[# RUBY_APPEND_OPTIONS($1)
 	for rb_opt in $2; do
@@ -321,7 +321,7 @@ AC_DEFUN([RUBY_APPEND_OPTIONS],
 AC_DEFUN([RUBY_PREPEND_OPTION],
 	[# RUBY_PREPEND_OPTION($1)
 	AS_CASE([" [$]{$1-} "],
-	[*' $2 '*], [], ['  '], [ $1="$2"], [ $1="$2 [$]$1"])])
+	[*" $2 "*], [], ['  '], [ $1="$2"], [ $1="$2 [$]$1"])])
 AC_DEFUN([RUBY_PREPEND_OPTIONS],
 	[# RUBY_PREPEND_OPTIONS($1)
 	unset rb_opts; for rb_opt in $2; do