diff --git a/Gemfile.lock b/Gemfile.lock
index dfac2c8..32e4bdf 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -8,21 +8,21 @@ PATH
 GEM
   remote: https://rubygems.org/
   specs:
-    activesupport (3.2.16)
-      i18n (~> 0.6, >= 0.6.4)
-      multi_json (~> 1.0)
-    atomic (1.1.14)
+    activesupport (4.1.0)
+      i18n (~> 0.6, >= 0.6.9)
+      json (~> 1.7, >= 1.7.7)
+      minitest (~> 5.1)
+      thread_safe (~> 0.1)
+      tzinfo (~> 1.1)
     i18n (0.6.9)
     json (1.8.1)
     minitest (5.2.2)
     minitest-rg (5.0.0)
       minitest (~> 5.0)
-    multi_json (1.8.4)
     rake (10.1.1)
     rdoc (4.1.1)
       json (~> 1.4)
-    thread_safe (0.1.3)
-      atomic
+    thread_safe (0.3.3)
     tzinfo (1.1.0)
       thread_safe (~> 0.1)
 
diff --git a/lib/business_time.rb b/lib/business_time.rb
index 9d3ce2c..f734318 100644
--- a/lib/business_time.rb
+++ b/lib/business_time.rb
@@ -2,6 +2,7 @@
 require 'active_support'
 require 'active_support/time'
 require 'time'
+require 'yaml'
 
 require 'business_time/config'
 require 'business_time/business_hours'
diff --git a/lib/business_time/config.rb b/lib/business_time/config.rb
index cc2ea18..2d156b4 100644
--- a/lib/business_time/config.rb
+++ b/lib/business_time/config.rb
@@ -76,7 +76,7 @@ class << self
       def end_of_workday(day=nil)
         if day
           wday = work_hours[int_to_wday(day.wday)]
-          wday ? (wday.last =~ /0{1,2}\:0{1,2}/ ? "23:59:59" : wday.last) : config[:end_of_workday]
+          wday ? (wday.last =~ /^0{1,2}\:0{1,2}$/ ? "23:59:59" : wday.last) : config[:end_of_workday]
         else
           config[:end_of_workday]
         end
diff --git a/test/test_calculating_business_duration.rb b/test/test_calculating_business_duration.rb
index 35adb97..2901b54 100644
--- a/test/test_calculating_business_duration.rb
+++ b/test/test_calculating_business_duration.rb
@@ -78,4 +78,20 @@
     }
     assert_equal 68.hours, friday.business_time_until(monday)
   end
+
+  it 'properly calculate overnight business time' do
+    BusinessTime::Config.work_hours = {
+      mon: ["08:00","20:00"],
+      tue: ["08:00","20:00"],
+    }
+    BusinessTime::Config.holidays = []
+
+    created_at = Time.local(2014, 05, 12, 20, 50) #yesterday night 20:50
+    published_at = Time.local(2014, 05, 13, 8, 10) #today morning 08:10
+    assert created_at.monday?
+    assert published_at.tuesday?
+
+    assert_equal 10.minutes, created_at.business_time_until(published_at)
+  end
+
 end
diff --git a/test/test_config.rb b/test/test_config.rb
index 0cb7e5e..c4ba17a 100644
--- a/test/test_config.rb
+++ b/test/test_config.rb
@@ -50,6 +50,18 @@
     assert_equal([1,2,4,5], BusinessTime::Config.weekdays.sort)
   end
 
+  it 'end of workday not freakout' do
+    BusinessTime::Config.work_hours = {
+      :mon=>["9:00","20:00"],
+      :tue=>["9:00","17:00"],
+      :thu=>["9:00","17:00"],
+      :fri=>["9:00","17:00"]
+    }
+
+    monday = Time.local(2014, 05, 12, 20, 50)
+    assert_equal "20:00", BusinessTime::Config.end_of_workday(monday)
+  end
+
   it "load config from YAML files" do
     yaml = <<-YAML
     business_time: