diff --git a/ChangeLog b/ChangeLog
index 39abcd6f2f..cbdcb852e4 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,6 +1,7 @@
 Thu Sep 21 19:04:34 2000  WATANABE Hirofumi  <eban@os.rim.or.jp>
 
-	* ext/extmk.rb (install_rb): check whether libdir is directory or not.
+	* ext/extmk.rb, lib/mkmf.rb (install_rb): check whether libdir is
+	  directory or not.
 
 Thu Sep 21 17:23:05 2000  Yukihiro Matsumoto  <matz@ruby-lang.org>
 
diff --git a/lib/mkmf.rb b/lib/mkmf.rb
index 47abd321bf..37e06a3a1a 100644
--- a/lib/mkmf.rb
+++ b/lib/mkmf.rb
@@ -129,11 +129,13 @@ def install_rb(mfile, dest, srcdir = nil)
   libdir = srcdir + "/" + libdir if srcdir
   path = []
   dir = []
-  Find.find(libdir) do |f|
-    next unless /\.rb$/ =~ f
-    f = f[libdir.length+1..-1]
-    path.push f
-    dir |= File.dirname(f)
+  if File.directory? libdir
+    Find.find(libdir) do |f|
+      next unless /\.rb$/ =~ f
+      f = f[libdir.length+1..-1]
+      path.push f
+      dir |= File.dirname(f)
+    end
   end
   for f in dir
     next if f == "."