diff --git a/tests/test_vagrant.py b/tests/test_vagrant.py
index de20dbe..60a2b62 100644
--- a/tests/test_vagrant.py
+++ b/tests/test_vagrant.py
@@ -596,7 +596,7 @@ def test_streaming_output(vm_dir):
     """
     Test streaming output of up or reload.
     """
-    test_string = "Waiting for machine to boot."
+    test_string = "Machine already provisioned"
     v = vagrant.Vagrant(vm_dir)
 
     with pytest.raises(subprocess.CalledProcessError):
diff --git a/vagrant/__init__.py b/vagrant/__init__.py
index 3ab465e..63f51e5 100644
--- a/vagrant/__init__.py
+++ b/vagrant/__init__.py
@@ -1039,7 +1039,6 @@ def _stream_vagrant_command(self, args):
                 env=self.env,
                 stdout=subprocess.PIPE,
                 stderr=err_fh,
-                bufsize=1,
             )
 
             # Iterate over output lines.