diff --git a/ChangeLog b/ChangeLog
index 4e0d76b21d..3d006ffeee 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+Sat Aug  7 17:18:34 2010  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* ext/extmk.rb (extract_makefile): follow the change of
+	  install-rb-default line format at r28850, which causes second
+	  run to create dummy makefiles.
+
 Sat Aug  7 14:08:44 2010  NARUSE, Yui  <naruse@ruby-lang.org>
 
 	* lib/mkmf.rb: change instance variable to global.
diff --git a/ext/extmk.rb b/ext/extmk.rb
index 916c3a0f02..c2b215425c 100755
--- a/ext/extmk.rb
+++ b/ext/extmk.rb
@@ -50,7 +50,7 @@ def extract_makefile(makefile, keep = true)
     return keep
   end
   installrb = {}
-  m.scan(/^install-rb-default:[ \t]*(\S+)\n\1:[ \t]*(\S+)/) {installrb[$2] = $1}
+  m.scan(/^install-rb-default:.*[ \t](\S+)(?:[ \t].*)?\n\1:[ \t]*(\S+)/) {installrb[$2] = $1}
   oldrb = installrb.keys.sort
   newrb = install_rb(nil, "").collect {|d, *f| f}.flatten.sort
   if target_prefix = m[/^target_prefix[ \t]*=[ \t]*\/(.*)/, 1]