diff --git a/middleman-core/lib/middleman-core/application.rb b/middleman-core/lib/middleman-core/application.rb
index 2d31d870..625e974e 100644
--- a/middleman-core/lib/middleman-core/application.rb
+++ b/middleman-core/lib/middleman-core/application.rb
@@ -11,7 +11,6 @@ require 'i18n'
 # Use ActiveSupport JSON
 require 'active_support/json'
 require 'active_support/core_ext/integer/inflections'
-require 'active_support/core_ext/float/rounding'
 
 # Simple callback library
 require 'vendored-middleman-deps/hooks-0.2.0/lib/hooks'
diff --git a/middleman-core/lib/middleman-core/logger.rb b/middleman-core/lib/middleman-core/logger.rb
index d8b23c9f..3ab3581e 100644
--- a/middleman-core/lib/middleman-core/logger.rb
+++ b/middleman-core/lib/middleman-core/logger.rb
@@ -1,12 +1,12 @@
 # Use the Ruby/Rails logger
 require 'active_support/notifications'
-require 'active_support/buffered_logger'
+require 'active_support/logger'
 require 'thread'
 
 module Middleman
 
   # The Middleman Logger
-  class Logger < ActiveSupport::BufferedLogger
+  class Logger < ActiveSupport::Logger
 
     def self.singleton(*args)
       if !@_logger || args.length > 0
diff --git a/middleman-core/middleman-core.gemspec b/middleman-core/middleman-core.gemspec
index 954a2325..3e56b1d6 100644
--- a/middleman-core/middleman-core.gemspec
+++ b/middleman-core/middleman-core.gemspec
@@ -30,7 +30,7 @@ Gem::Specification.new do |s|
   s.add_dependency("thor", [">= 0.15.2", "< 2.0"])
 
   # Helpers
-  s.add_dependency("activesupport", ["~> 3.2.6"])
+  s.add_dependency("activesupport", ["~> 4.0.1"])
 
   # Watcher
   s.add_dependency("listen", ["~> 1.1"])