diff --git a/lib/flowerbox.rb b/lib/flowerbox.rb
index fcd2294..1e767fe 100644
--- a/lib/flowerbox.rb
+++ b/lib/flowerbox.rb
@@ -1,5 +1,6 @@
 require "flowerbox/version"
 require 'rainbow'
+require 'forwardable'
 
 module Flowerbox
   require 'flowerbox/core_ext/module'
@@ -16,6 +17,7 @@ module Flowerbox
   require 'flowerbox/gathered_result'
 
   require 'flowerbox/reporter'
+  require 'flowerbox/configuration'
 
   if defined?(Rails::Engine)
     require 'flowerbox/rails/engine'
@@ -24,62 +26,20 @@ module Flowerbox
   CACHE_DIR = 'tmp/sprockets'
 
   class << self
-    attr_writer :reporters
-    attr_accessor :port
-
     def reset!
-      @spec_patterns = nil
-      @spec_files = nil
-      @asset_paths = nil
-      @reporters = nil
-      @port = nil
+      @configuration = nil
     end
 
-    def spec_patterns
-      @spec_patterns ||= []
-    end
-
-    def asset_paths
-      @asset_paths ||= []
-    end
-
-    def reporters
-      @reporters ||= []
-    end
-
-    def additional_files
-      @additional_files ||= []
-    end
-
-    def test_with(what)
-      self.test_environment = Flowerbox::TestEnvironment.for(what)
-    end
-
-    def run_with(*whats)
-      self.runner_environment = whats.flatten.collect { |what| Flowerbox::Runner.for(what.to_s) }
-    end
-
-    def report_with(*whats)
-      self.reporters = whats.flatten.collect { |what| Flowerbox::Reporter.for(what.to_s) }
+    def configuration
+      @configuration ||= Flowerbox::Configuration.new
     end
 
     def path
       Pathname(File.expand_path('../..', __FILE__))
     end
 
-    attr_accessor :test_environment, :runner_environment, :bare_coffeescript, :server
-
-    def configure
-      yield self
-
-      if spec_patterns.empty?
-        spec_patterns << "**/*_spec*"
-        spec_patterns << "*/*_spec*"
-      end
-
-      if reporters.empty?
-        reporters << Flowerbox::Reporter.for(:progress)
-      end
+    def configure(&block)
+      configuration.configure(&block)
     end
 
     def bare_coffeescript
@@ -119,6 +79,14 @@ module Flowerbox
     def cache_dir
       File.join(CACHE_DIR, Flowerbox.test_environment.name)
     end
+
+    def method_missing(method, *args)
+      if configuration.respond_to?(method)
+        configuration.send(method, *args)
+      else
+        super
+      end
+    end
   end
 end
 
diff --git a/lib/flowerbox/configuration.rb b/lib/flowerbox/configuration.rb
new file mode 100644
index 0000000..1ba758a
--- /dev/null
+++ b/lib/flowerbox/configuration.rb
@@ -0,0 +1,54 @@
+module Flowerbox
+  class Configuration
+    attr_writer :reporters, :backtrace_filter
+    attr_accessor :port
+
+    attr_accessor :test_environment, :runner_environment, :bare_coffeescript, :server
+
+    def spec_patterns
+      @spec_patterns ||= []
+    end
+
+    def asset_paths
+      @asset_paths ||= []
+    end
+
+    def reporters
+      @reporters ||= []
+    end
+
+    def additional_files
+      @additional_files ||= []
+    end
+
+    def backtrace_filter
+      @backtrace_filter ||= []
+    end
+
+    def test_with(what)
+      self.test_environment = Flowerbox::TestEnvironment.for(what)
+    end
+
+    def run_with(*whats)
+      self.runner_environment = whats.flatten.collect { |what| Flowerbox::Runner.for(what.to_s) }
+    end
+
+    def report_with(*whats)
+      self.reporters = whats.flatten.collect { |what| Flowerbox::Reporter.for(what.to_s) }
+    end
+
+    def configure
+      yield self
+
+      if spec_patterns.empty?
+        spec_patterns << "**/*_spec*"
+        spec_patterns << "*/*_spec*"
+      end
+
+      if reporters.empty?
+        reporters << Flowerbox::Reporter.for(:progress)
+      end
+    end
+  end
+end
+
diff --git a/lib/flowerbox/result/failure_message.rb b/lib/flowerbox/result/failure_message.rb
index 27f325a..d6a8084 100644
--- a/lib/flowerbox/result/failure_message.rb
+++ b/lib/flowerbox/result/failure_message.rb
@@ -35,11 +35,13 @@ module Flowerbox::Result
     end
 
     def filtered_stack
-      stack.collect do |line|
+      stack.reject { |line|
+        Flowerbox.backtrace_filter.any? { |filter| line[filter] }
+      }.collect { |line|
         line.gsub(%r{\.coffee:(\d+)}) do |_|
           ".coffee:~#{($1.to_i * 0.67 + 1).to_i}"
         end
-      end
+      }
     end
 
     def first_local_stack
diff --git a/lib/flowerbox/run/base.rb b/lib/flowerbox/run/base.rb
index fe2e134..418c3a2 100644
--- a/lib/flowerbox/run/base.rb
+++ b/lib/flowerbox/run/base.rb
@@ -35,14 +35,16 @@ module Flowerbox::Run
     def sprockets
       require 'flowerbox/sprockets_handler'
 
-      Flowerbox::SprocketsHandler.new(
-        :asset_paths => [
-          Flowerbox.path.join("lib/assets/javascripts"),
-          Flowerbox.path.join("vendor/assets/javascripts"),
-          @dir,
-          Flowerbox.asset_paths
-        ].flatten
-      )
+      Flowerbox::SprocketsHandler.new(:asset_paths => asset_paths)
+    end
+
+    def asset_paths
+      [
+        Flowerbox.path.join("lib/assets/javascripts"),
+        Flowerbox.path.join("vendor/assets/javascripts"),
+        @dir,
+        Flowerbox.asset_paths
+      ].flatten
     end
 
     def spec_files
diff --git a/lib/flowerbox/unique_asset_list.rb b/lib/flowerbox/unique_asset_list.rb
index 03353a7..47fe21b 100644
--- a/lib/flowerbox/unique_asset_list.rb
+++ b/lib/flowerbox/unique_asset_list.rb
@@ -6,10 +6,19 @@ module Flowerbox
       super([])
 
       @sprockets = sprockets
+
+      @included = {}
     end
 
     def add(files)
-      [ files ].flatten.each { |file| self << file if !include?(file) }
+      [ files ].flatten.each do |file|
+        self << file if !included?(file)
+      end
+    end
+
+    def <<(file)
+      super(file)
+      @included[file.pathname.to_s] = true
     end
 
     def to_json
@@ -17,8 +26,8 @@ module Flowerbox
     end
 
     private
-    def include?(file)
-      any? { |other_file| other_file.pathname.to_s == file.pathname.to_s }
+    def included?(file)
+      @included[file.pathname.to_s]
     end
   end
 end