diff --git a/actionpack/lib/action_controller/vendor/html-scanner/html/selector.rb b/actionpack/lib/action_controller/vendor/html-scanner/html/selector.rb
index 376bb87..e2c49c2 100644
--- a/actionpack/lib/action_controller/vendor/html-scanner/html/selector.rb
+++ b/actionpack/lib/action_controller/vendor/html-scanner/html/selector.rb
@@ -556,7 +556,7 @@ module HTML
         end
 
         # Attribute value.
-        next if statement.sub!(/^\[\s*([[:alpha:]][\w\-]*)\s*((?:[~|^$*])?=)?\s*('[^']*'|"[^*]"|[^\]]*)\s*\]/) do |match|
+        next if statement.sub!(/^\[\s*([[:alpha:]][\w\-:]*)\s*((?:[~|^$*])?=)?\s*('[^']*'|"[^*]"|[^\]]*)\s*\]/) do |match|
           name, equality, value = $1, $2, $3
           if value == "?"
             value = values.shift
diff --git a/actionpack/test/controller/assert_select_test.rb b/actionpack/test/controller/assert_select_test.rb
index ed8c442..ffb5956 100644
--- a/actionpack/test/controller/assert_select_test.rb
+++ b/actionpack/test/controller/assert_select_test.rb
@@ -248,6 +248,11 @@ class AssertSelectTest < ActionController::TestCase
     end
   end
 
+  def test_elect_with_xml_namespace_attributes
+    render_html %Q{<link xlink:href="http://nowhere.com"></link>}
+    assert_nothing_raised { assert_select "link[xlink:href=http://nowhere.com]" }
+  end
+
   #
   # Test css_select.
   #