diff --git a/tests/hwsim/rfkill.py b/tests/hwsim/rfkill.py
index f08cf50c5..72b2527fe 100755
--- a/tests/hwsim/rfkill.py
+++ b/tests/hwsim/rfkill.py
@@ -126,7 +126,7 @@ class RFKill(object):
     @classmethod
     def list(cls):
         res = []
-        rfk = open('/dev/rfkill', 'rb')
+        rfk = open('/dev/rfkill', 'rb', buffering=0)
         fd = rfk.fileno()
         flgs = fcntl.fcntl(fd, fcntl.F_GETFL)
         fcntl.fcntl(fd, fcntl.F_SETFL, flgs | os.O_NONBLOCK)