diff --git a/lib/benchmark.rb b/lib/benchmark.rb
index bd3b072..9c42c23 100644
--- a/lib/benchmark.rb
+++ b/lib/benchmark.rb
@@ -290,9 +290,9 @@ module Benchmark
   # Returns the elapsed real time used to execute the given block.
   #
   def realtime # :yield:
-    r0 = Time.now
+    r0 = Process.clock_gettime(Process::CLOCK_MONOTONIC)
     yield
-    Time.now - r0
+    Process.clock_gettime(Process::CLOCK_MONOTONIC) - r0
   end
 
   module_function :benchmark, :measure, :realtime, :bm, :bmbm
diff --git a/test/benchmark/test_benchmark.rb b/test/benchmark/test_benchmark.rb
index b2239d4..7e9653d 100644
--- a/test/benchmark/test_benchmark.rb
+++ b/test/benchmark/test_benchmark.rb
@@ -152,4 +152,9 @@ BENCH
     t.add! { sleep 0.1 }
     assert_not_equal(0, t.real)
   end
+
+  def test_realtime_output
+    realtime = Benchmark.realtime { sleep 0.001 }
+    assert_in_delta 0.001, realtime
+  end
 end