diff --git a/ChangeLog b/ChangeLog
index 078efe4880..074ad90e23 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+Wed Sep 20 23:17:41 2006  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* common.mk (pre-install-doc): create data directory before install.
+
+	* lib/mkmf.rb (dir_re): fixed typo.
+
+	* lib/mkmf.rb (install_dirs): remove extra slash.
+
 Wed Sep 20 22:41:45 2006  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* numeric.c (fix_mul): typo again.  patch from Tadashi Saito
diff --git a/common.mk b/common.mk
index 545886d819..a96578be82 100644
--- a/common.mk
+++ b/common.mk
@@ -236,6 +236,7 @@ rdoc: $(PROGRAM) PHONY
 	$(RUNRUBY) "$(srcdir)/bin/rdoc" --all --ri --op "$(RDOCOUT)" "$(srcdir)"
 
 pre-install-doc:: PHONY
+	$(RUNRUBY) -run -e mkdir -- -p "$(RIDATADIR)"
 
 post-install-doc:: PHONY
 
diff --git a/lib/mkmf.rb b/lib/mkmf.rb
index 97a6036700..6caeef3d54 100644
--- a/lib/mkmf.rb
+++ b/lib/mkmf.rb
@@ -68,7 +68,7 @@ def config_string(key, config = CONFIG)
 end
 
 def dir_re(dir)
-  Regexp.new('\$(?:\('+dir+'\)|\{'+dir+'\})(?:\$\(target_prefix\)|\{target_prefix\})?')
+  Regexp.new('\$(?:\('+dir+'\)|\{'+dir+'\})(?:\$(?:\(target_prefix\)|\{target_prefix\}))?')
 end
 
 INSTALL_DIRS = [
@@ -84,7 +84,7 @@ def install_dirs(target_prefix = nil)
   if $extout
     dirs = [
       ['RUBYCOMMONDIR', '$(extout)/common'],
-      ['RUBYLIBDIR',    '$(RUBYCOMMONDIR)/$(target_prefix)'],
+      ['RUBYLIBDIR',    '$(RUBYCOMMONDIR)$(target_prefix)'],
       ['RUBYARCHDIR',   '$(extout)/$(arch)$(target_prefix)'],
       ['extout',        "#$extout"],
       ['extout_prefix', "#$extout_prefix"],