diff --git a/init.rb b/init.rb
index 9d63c63..8940541 100644
--- a/init.rb
+++ b/init.rb
@@ -2,8 +2,10 @@ require 'redmine'
 
 # Patches to the Redmine core.
 require 'dispatcher'
+require 'overhead_time_entry_patch'
 require 'overhead_time_entry_activity_patch'
 Dispatcher.to_prepare do
+  TimeEntry.send(:include, OverheadTimeEntryPatch)
   TimeEntryActivity.send(:include, OverheadTimeEntryActivityPatch)
 end
 
diff --git a/lib/overhead_time_entry_patch.rb b/lib/overhead_time_entry_patch.rb
new file mode 100644
index 0000000..1e5b12e
--- /dev/null
+++ b/lib/overhead_time_entry_patch.rb
@@ -0,0 +1,11 @@
+require_dependency 'time_entry'
+
+module OverheadTimeEntryPatch
+  def self.included(base)
+    base.class_eval do
+      unloadable
+      delegate :billable?, :to => :activity
+    end
+  end
+end
+
diff --git a/spec/lib/overhead_time_entry_patch_spec.rb b/spec/lib/overhead_time_entry_patch_spec.rb
new file mode 100644
index 0000000..fc141b0
--- /dev/null
+++ b/spec/lib/overhead_time_entry_patch_spec.rb
@@ -0,0 +1,21 @@
+require File.dirname(__FILE__) + '/../spec_helper'
+
+describe TimeEntry, 'billable?' do
+  before(:each) do
+    @time_entry = TimeEntry.new
+  end
+
+  it 'should be true if the activity is considered billable' do
+    @time_entry.should_receive(:activity).and_return do
+      mock_model(TimeEntryActivity, :billable? => true)
+    end
+    @time_entry.billable?.should be_true
+  end
+
+  it 'should be false if the activity is considered overhead' do
+    @time_entry.should_receive(:activity).and_return do
+      mock_model(TimeEntryActivity, :billable? => false)
+    end
+    @time_entry.billable?.should be_false
+  end
+end