1 files changed, 1 insertions, 0 deletions
diff --git a/lib/open3.rb b/lib/open3.rb
index 33701bbfc0..a6e6c5d62b 100644
--- a/lib/open3.rb
+++ b/lib/open3.rb
@@ -40,6 +40,7 @@ module Open3
     pe[1].close
     Process.waitpid(pid)
     pi = [pw[1], pr[0], pe[0]]
+    pw[1].sync = true
     if defined? yield
       begin
 	return yield(*pi)