diff --git a/Gemfile b/Gemfile
index ba16eab..61000a6 100644
--- a/Gemfile
+++ b/Gemfile
@@ -2,3 +2,4 @@ source 'http://rubygems.org'
 
 gem 'ruby-debug19', '~> 0.11.6', :require => 'ruby-debug'
 gem 'rspec',        '~> 2.7'
+gem 'timecop',      '~> 0.3'
diff --git a/Gemfile.lock b/Gemfile.lock
index 066cff1..289d640 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -24,6 +24,7 @@ GEM
       ruby-debug-base19 (>= 0.11.19)
     ruby_core_source (0.1.5)
       archive-tar-minitar (>= 0.5.2)
+    timecop (0.3.5)
 
 PLATFORMS
   ruby
@@ -31,3 +32,4 @@ PLATFORMS
 DEPENDENCIES
   rspec (~> 2.7)
   ruby-debug19 (~> 0.11.6)
+  timecop (~> 0.3)
diff --git a/lib/reactorb/reactor.rb b/lib/reactorb/reactor.rb
index 70332ad..d04dd57 100644
--- a/lib/reactorb/reactor.rb
+++ b/lib/reactorb/reactor.rb
@@ -36,7 +36,7 @@ def at(time_or_number, *args, &block)
   end
 
   def call_timers
-    now = Time.now.to_i
+    now = self.class.now
     while @timers.any? && @timers.first_key <= now
       block, args = @timers.shift
       block.call(*args)
@@ -47,6 +47,10 @@ def empty?
     @timers.empty?
   end
 
+  def self.now
+    Time.now.to_i
+  end
+
 end
 
 class ShiftableHash < Hash
diff --git a/spec/reactor_spec.rb b/spec/reactor_spec.rb
index 549b170..af81d37 100644
--- a/spec/reactor_spec.rb
+++ b/spec/reactor_spec.rb
@@ -16,6 +16,12 @@
 end
 
 describe Reactor, "#run" do
+  let(:now) { 1324311324 }
+  before do
+    start = now
+    Timecop.freeze(start)
+    Reactor.stub(:now) { start += 1 }
+  end
   it "should execute block passed" do
     expect { subject.run{|r| raise "foo" } }.to raise_error "foo"
   end
@@ -45,19 +51,16 @@
   end
   context "with time based events added in the future" do
     it "should fire events" do
-      now = Time.now.to_i + 1
       tally = 0
       subject.run do |r|
         r.at(now+1){ tally += 1}
         r.at(now+2){ tally += 1}
-        r.at(now+3){ r.stop }
       end
       tally.should == 2
     end
   end
   context "stopped with time based events added in the future" do
     it "should not fire events" do
-      now = Time.now.to_i + 1
       tally = 0
       subject.run do |r|
         r.at(now+1){ r.stop }
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index f70d752..3a9ffc3 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -1,4 +1,5 @@
 require 'rspec'
+require 'timecop'
 require 'reactorb'
 
 # Requires supporting files with custom matchers and macros, etc,