diff --git a/tool/rbinstall.rb b/tool/rbinstall.rb
index 266d717..0e9f39a 100755
--- a/tool/rbinstall.rb
+++ b/tool/rbinstall.rb
@@ -515,7 +515,7 @@ install?(:ext, :comm, :gem) do
     version = open(src) {|f| f.find {|s| /^\s*\w*VERSION\s*=(?!=)/ =~ s}} or next
     version = version.split(%r"=\s*", 2)[1].strip[/\A([\'\"])(.*?)\1/, 2]
     puts "#{" "*30}#{name} #{version}"
-    open_for_install(File.join(destdir, "#{name}.gemspec"), $data_mode) do
+    open_for_install(File.join(destdir, "#{name}-#{version}.gemspec"), $data_mode) do
       <<-GEMSPEC
 Gem::Specification.new do |s|
   s.name = #{name.dump}