diff --git a/ChangeLog b/ChangeLog
index b8b9b02ed0..c3fa00b460 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+Fri Jul 13 22:26:09 2001  Akinori MUSHA  <knu@iDaemons.org>
+
+	* lib/mkmf.rb: use File::split to split a target into a prefix and
+	  a module name.  This also works around a just found bug of
+	  String#rindex.
+
+	* ext/extmk.rb.in: ditto.
+
 Thu Jul 12 15:11:48 2001  WATANABE Hirofumi  <eban@ruby-lang.org>
 
 	* ext/socket/socket.c (ruby_connect): workaround for the setup of
diff --git a/ext/extmk.rb.in b/ext/extmk.rb.in
index 941d9d5dab..adbc350b80 100644
--- a/ext/extmk.rb.in
+++ b/ext/extmk.rb.in
@@ -362,9 +362,9 @@ end
 
 def create_makefile(target)
   $target = target
-  if target.rindex(%r!/!)
-    target = $'
-    target_prefix = "/"+$`
+  if target.include?('/')
+    target_prefix, target = File.split(target)
+    target_prefix[0,0] = '/'
   else
     target_prefix = ""
   end
diff --git a/lib/mkmf.rb b/lib/mkmf.rb
index fec789e4e8..e28cd49869 100644
--- a/lib/mkmf.rb
+++ b/lib/mkmf.rb
@@ -367,9 +367,9 @@ def create_makefile(target, srcdir = File.dirname($0))
   print "creating Makefile\n"
   rm_f "conftest*"
   STDOUT.flush
-  if target.rindex(%r!/!) #/
-    target = $'
-    target_prefix = "/"+$`
+  if target.include?('/')
+    target_prefix, target = File.split(target)
+    target_prefix[0,0] = '/'
   else
     target_prefix = ""
   end