diff --git a/plugins/communicators/ssh/communicator.rb b/plugins/communicators/ssh/communicator.rb
index 7e0e9af37e2..1ba3d0f2144 100644
--- a/plugins/communicators/ssh/communicator.rb
+++ b/plugins/communicators/ssh/communicator.rb
@@ -251,7 +251,7 @@ def ready?
 
           # Write out the private key in the data dir so that the
           # machine automatically picks it up.
-          @machine.data_dir.join("private_key").open("w+") do |f|
+          @machine.data_dir.join("private_key").open("wb+") do |f|
             f.write(priv)
           end