diff --git a/lib/benchmark.rb b/lib/benchmark.rb
index 4cfc0d8a5b..361bca3cad 100644
--- a/lib/benchmark.rb
+++ b/lib/benchmark.rb
@@ -163,8 +163,8 @@ module Benchmark
   #
 
   def benchmark(caption = "", label_width = nil, format = nil, *labels) # :yield: report
-    sync = STDOUT.sync
-    STDOUT.sync = true
+    sync = $stdout.sync
+    $stdout.sync = true
     label_width ||= 0
     label_width += 1
     format ||= FORMAT
@@ -176,7 +176,7 @@ module Benchmark
     }
     report.list
   ensure
-    STDOUT.sync = sync unless sync.nil?
+    $stdout.sync = sync unless sync.nil?
   end
 
 
@@ -247,8 +247,8 @@ module Benchmark
     job = Job.new(width)
     yield(job)
     width = job.width + 1
-    sync = STDOUT.sync
-    STDOUT.sync = true
+    sync = $stdout.sync
+    $stdout.sync = true
 
     # rehearsal
     puts 'Rehearsal '.ljust(width+CAPTION.length,'-')
@@ -268,7 +268,7 @@ module Benchmark
       Benchmark.measure(label, &item).tap { |res| print res }
     }
   ensure
-    STDOUT.sync = sync unless sync.nil?
+    $stdout.sync = sync unless sync.nil?
   end
 
   #