diff --git a/ChangeLog b/ChangeLog
index 35ba94492b..1b7c13349c 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,4 +1,8 @@
-Sun Dec 13 16:29:22 2015  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+Sun Dec 13 16:41:01 2015  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* configure.in (BOOTSTRAPRUBY): make BASERUBY full path before
+	  building ruby to get rid of unexpectedly invoking built ruby.
+	  [ruby-core:72065] [Bug #11807]
 
 	* configure.in (BOOTSTRAPRUBY): use MINIRUBY but not BASERUBY
 	  unless cross compiling.  [ruby-core:72065] [Bug #11807]
diff --git a/configure.in b/configure.in
index 5207fad759..cbefd7c1db 100644
--- a/configure.in
+++ b/configure.in
@@ -43,7 +43,7 @@ AC_ARG_WITH(baseruby,
 		AS_CASE(["$withval"],[*ruby*],[BASERUBY=$withval],[AC_MSG_ERROR(need ruby)])
 	],
 	[
-		BASERUBY="ruby"
+		AC_PATH_PROG([BASERUBY], [ruby], [false])
 	])
 if test "`RUBYOPT=- $BASERUBY -e 'print 42' 2>/dev/null`" = 42; then
     if test "`RUBYOPT=- $BASERUBY --disable=gems -e 'print 42' 2>/dev/null`" = 42; then