diff --git a/test/source/environment.html b/test/source/environment.html
new file mode 100644
index 00000000..b875a61f
--- /dev/null
+++ b/test/source/environment.html
@@ -0,0 +1,5 @@
+---
+title: I'm a Jekyll environment exchequer
+---
+
+{{ jekyll.environment }}
diff --git a/test/test_filters.rb b/test/test_filters.rb
index e56a88ce..22734378 100644
--- a/test/test_filters.rb
+++ b/test/test_filters.rb
@@ -137,7 +137,7 @@ class TestFilters < Test::Unit::TestCase
             assert_equal 2, g["items"].size
           when ""
             assert g["items"].is_a?(Array), "The list of grouped items for '' is not an Array."
-            assert_equal 10, g["items"].size
+            assert_equal 11, g["items"].size
           end
         end
       end
diff --git a/test/test_site.rb b/test/test_site.rb
index 94263491..de02b8dd 100644
--- a/test/test_site.rb
+++ b/test/test_site.rb
@@ -166,6 +166,7 @@ class TestSite < Test::Unit::TestCase
         coffeescript.coffee
         contacts.html
         deal.with.dots.html
+        environment.html
         exploit.md
         foo.md
         index.html
@@ -407,5 +408,35 @@ class TestSite < Test::Unit::TestCase
       end
 
     end
+
+    context "manipulating the Jekyll environment" do
+      setup do
+        @site = Site.new(site_configuration)
+        @site.process
+        @page = @site.pages.find { |p| p.name == "environment.html" }
+      end
+
+      should "default to 'development'" do
+        assert_equal "development", @page.content.strip
+      end
+
+      context "in production" do
+        setup do
+          ENV["JEKYLL_ENV"] = "production"
+          @site = Site.new(site_configuration)
+          @site.process
+          @page = @site.pages.find { |p| p.name == "environment.html" }
+        end
+
+        teardown do
+          ENV.delete("JEKYLL_ENV")
+        end
+
+        should "be overridden by JEKYLL_ENV" do
+          assert_equal "production", @page.content.strip
+        end
+      end
+    end
+
   end
 end