diff --git a/test/system_timer_functional_test.rb b/test/system_timer_functional_test.rb
index bdba81c..ce92384 100644
--- a/test/system_timer_functional_test.rb
+++ b/test/system_timer_functional_test.rb
@@ -50,7 +50,12 @@
       SystemTimer.timeout_after(1) {sleep 5}
     end
   end
-  
+  test "timeout_after raises CustomTimeout if block takes too long" do
+    assert_raises(CustomTimeout) do
+      SystemTimer.timeout_after(1,CustomTimeout) {sleep 5}
+    end
+  end
+ 
   test "timeout_after does not raises Timeout Error if block completes in time" do
     SystemTimer.timeout_after(5) {sleep 1}
   end
@@ -257,4 +262,4 @@ def assert_timeout_within(expected_timeout_in_seconds,
            "Timed out after #{elapsed} seconds, expected #{expected_timeout_in_seconds}"
   end
   
-end
\ No newline at end of file
+end
diff --git a/test/system_timer_unit_test.rb b/test/system_timer_unit_test.rb
index 1360eb7..c371e41 100644
--- a/test/system_timer_unit_test.rb
+++ b/test/system_timer_unit_test.rb
@@ -13,6 +13,17 @@
     SystemTimer.timeout_after(5) {}    
   end
 
+  test "timeout_after registers a new timer with a custom timeout exception in the timer pool" do
+    pool = stub_everything
+    Thread.stubs(:current).returns(:the_current_thread)
+    SystemTimer.stubs(:timer_pool).returns(pool)
+    SystemTimer.stubs(:install_next_timer)
+    SystemTimer.stubs(:restore_original_configuration)
+
+    pool.expects(:add_timer).with(5,CustomTimeout).returns(stub_everything)
+    SystemTimer.timeout_after(5,CustomTimeout) {}    
+  end
+
   test "timeout_after installs a system timer saving the previous " +
        "configuration when there is only one timer" do
          
diff --git a/test/test_helper.rb b/test/test_helper.rb
index ed09991..3739f30 100644
--- a/test/test_helper.rb
+++ b/test/test_helper.rb
@@ -8,3 +8,5 @@
 require 'stringio'
 require "open-uri"
 require 'system_timer'
+class CustomTimeout < Exception
+end