diff --git a/lib/bypass/filter.rb b/lib/bypass/filter.rb
index 16e7fa7..054b644 100644
--- a/lib/bypass/filter.rb
+++ b/lib/bypass/filter.rb
@@ -25,5 +25,11 @@ def gsub_urls(text, &block)
         yield(match.to_s)
       end
     end
+
+    def parse_uri(uri)
+      Bypass::URI.parse(uri)
+    rescue => ex
+      nil
+    end
   end
 end
\ No newline at end of file
diff --git a/lib/bypass/html_filter.rb b/lib/bypass/html_filter.rb
index feb9830..7937b00 100644
--- a/lib/bypass/html_filter.rb
+++ b/lib/bypass/html_filter.rb
@@ -6,8 +6,10 @@ class HTMLFilter < Filter
     def replace(&block)
       parsed_content.traverse do |node|
         if node.name == "a" && href = node.get_attribute("href")
-          url = yield(Bypass::URI.parse(href))
-          node.set_attribute("href", url.to_s)
+          if parsed_href = parse_uri(href)
+            url = yield(parsed_href)
+            node.set_attribute("href", url.to_s)
+          end
         end
       end
     end
diff --git a/lib/bypass/text_filter.rb b/lib/bypass/text_filter.rb
index 0e3877e..bc45be3 100644
--- a/lib/bypass/text_filter.rb
+++ b/lib/bypass/text_filter.rb
@@ -2,8 +2,10 @@ module Bypass
   class TextFilter < Filter
 
     def replace(&block)
-      @content = gsub_urls(content) do |url| 
-        yield(Bypass::URI.parse(url)).to_s
+      @content = gsub_urls(content) do |url|
+        if parsed_url = parse_uri(url)
+          yield(parsed_url).to_s
+        end
       end
     end
 
diff --git a/test/detour/filter_test.rb b/test/bypass/filter_test.rb
similarity index 100%
rename from test/detour/filter_test.rb
rename to test/bypass/filter_test.rb
diff --git a/test/detour/html_filter_test.rb b/test/bypass/html_filter_test.rb
similarity index 90%
rename from test/detour/html_filter_test.rb
rename to test/bypass/html_filter_test.rb
index 781f381..1b97bbc 100644
--- a/test/detour/html_filter_test.rb
+++ b/test/bypass/html_filter_test.rb
@@ -16,6 +16,13 @@ class Bypass::HTMLFilterTest < Test::Unit::TestCase
       filter.replace { "foo" }
       assert_equal "<a>Yahoo</a>", filter.content
     end
+
+    should "skip malformed URLs" do
+      text = "<a href=\"http://#\">Yahoo</a>"
+      filter = Bypass::HTMLFilter.new(text)
+      filter.replace { "foo" }
+      assert_equal text, filter.content
+    end
   end
 
   context "#auto_link" do
diff --git a/test/detour/text_filter_test.rb b/test/bypass/text_filter_test.rb
similarity index 84%
rename from test/detour/text_filter_test.rb
rename to test/bypass/text_filter_test.rb
index c363536..09457b8 100644
--- a/test/detour/text_filter_test.rb
+++ b/test/bypass/text_filter_test.rb
@@ -30,5 +30,12 @@ class Bypass::TextFilterTest < Test::Unit::TestCase
       filter.replace { "foo" }
       assert_equal "foo,", filter.content
     end
+
+    should "skip malformed URLs" do
+      text = "http://#"
+      filter = Bypass::TextFilter.new(text)
+      filter.replace { "foo" }
+      assert_equal text, filter.content
+    end
   end
 end
\ No newline at end of file
diff --git a/test/detour/uri_test.rb b/test/bypass/uri_test.rb
similarity index 100%
rename from test/detour/uri_test.rb
rename to test/bypass/uri_test.rb