diff --git a/tool/rbinstall.rb b/tool/rbinstall.rb
index 8534cf75a3..ee3b0c96be 100755
--- a/tool/rbinstall.rb
+++ b/tool/rbinstall.rb
@@ -1018,6 +1018,7 @@ install?(:ext, :comm, :gem, :'bundled-gems') do
   end
 
   installed_gems = {}
+  skipped = {}
   options = {
     :install_dir => install_dir,
     :bin_dir => with_destdir(bindir),
@@ -1048,11 +1049,20 @@ install?(:ext, :comm, :gem, :'bundled-gems') do
     path = "#{srcdir}/.bundle/specifications/#{gem_name}.gemspec"
     unless File.exist?(path)
       path = "#{srcdir}/.bundle/gems/#{gem_name}/#{gem_name}.gemspec"
-      next unless File.exist?(path)
+      unless File.exist?(path)
+         skipped[gem_name] = "gemspec not found"
+         next
+      end
     end
     spec = load_gemspec(path, "#{srcdir}/.bundle/gems/#{gem_name}")
-    next unless spec.platform == Gem::Platform::RUBY
-    next unless spec.full_name == gem_name
+    unless spec.platform == Gem::Platform::RUBY
+      skipped[gem_name] = "not ruby platform (#{spec.platform})"
+      next
+    end
+    unless spec.full_name == gem_name
+      skipped[gem_name] = "full name unmatch #{spec.full_name}"
+      next
+    end
     spec.extension_dir = "#{extensions_dir}/#{spec.full_name}"
     package = RbInstall::DirPackage.new spec
     ins = RbInstall::UnpackedInstaller.new(package, options)
@@ -1110,6 +1120,7 @@ installs = $install.map do |inst|
 end
 installs.flatten!
 installs -= $exclude.map {|exc| $install_procs[exc]}.flatten
+puts "Installing to #$destdir" unless installs.empty?
 installs.each do |block|
   dir = Dir.pwd
   begin