diff --git a/lib/jekyll/post.rb b/lib/jekyll/post.rb
index 5502994c..bafb7257 100644
--- a/lib/jekyll/post.rb
+++ b/lib/jekyll/post.rb
@@ -131,7 +131,7 @@ module Jekyll
           "title"      => CGI.escape(slug),
           "i_day"      => date.strftime("%d").to_i.to_s,
           "i_month"    => date.strftime("%m").to_i.to_s,
-          "categories" => categories.join('/'),
+          "categories" => categories.map {|c| URI.escape(c) }.join('/'),
           "output_ext" => self.output_ext
         }.inject(template) { |result, token|
           result.gsub(/:#{Regexp.escape token.first}/, token.last)
diff --git a/test/test_post.rb b/test/test_post.rb
index 1c3ea641..245c30b4 100644
--- a/test/test_post.rb
+++ b/test/test_post.rb
@@ -141,6 +141,19 @@ class TestPost < Test::Unit::TestCase
           end
         end
 
+        context "with space (categories)" do
+          setup do
+            @post.categories << "French cuisine"
+            @post.categories << "Belgian beer"
+            @post.process(@fake_file)
+          end
+
+          should "process the url correctly" do
+            assert_equal "/:categories/:year/:month/:day/:title.html", @post.template
+            assert_equal "/French%20cuisine/Belgian%20beer/2008/09/09/foo-bar.html", @post.url
+          end
+        end
+
         context "with none style" do
           setup do
             @post.site.permalink_style = :none