diff --git a/qubes/tests/extra.py b/qubes/tests/extra.py
index a1e0f03e..91a26495 100644
--- a/qubes/tests/extra.py
+++ b/qubes/tests/extra.py
@@ -42,6 +42,8 @@ class ProcessWrapper(object):
         return setattr(self._proc, key, value)
 
     def communicate(self, input=None):
+        if self._proc.stdin is not None and input is None:
+            input = b''
         return self._loop.run_until_complete(self._proc.communicate(input))
 
     def wait(self):
diff --git a/qubes/tests/vm/qubesvm.py b/qubes/tests/vm/qubesvm.py
index 2f27cb13..6f0a8319 100644
--- a/qubes/tests/vm/qubesvm.py
+++ b/qubes/tests/vm/qubesvm.py
@@ -2017,7 +2017,7 @@ class TC_90_QubesVM(QubesVMTestsMixin, qubes.tests.QubesTestCase):
                 stdout=subprocess.PIPE,
                 stderr=subprocess.PIPE,
                 stdin=subprocess.PIPE)
-            communicate_mock.assert_called_once_with(input=None)
+            communicate_mock.assert_called_once_with(input=b'')
             self.assertEqual(value, (b'stdout', b'stderr'))
 
         func_mock.reset_mock()
@@ -2045,7 +2045,7 @@ class TC_90_QubesVM(QubesVMTestsMixin, qubes.tests.QubesTestCase):
                 stdout=subprocess.PIPE,
                 stderr=subprocess.PIPE,
                 stdin=subprocess.PIPE)
-            communicate_mock.assert_called_once_with(input=None)
+            communicate_mock.assert_called_once_with(input=b'')
             self.assertEqual(exc.exception.returncode, 1)
             self.assertEqual(exc.exception.output, b'stdout')
             self.assertEqual(exc.exception.stderr, b'stderr')
diff --git a/qubes/vm/qubesvm.py b/qubes/vm/qubesvm.py
index 3ed3aed1..395614f5 100644
--- a/qubes/vm/qubesvm.py
+++ b/qubes/vm/qubesvm.py
@@ -1435,6 +1435,9 @@ class QubesVM(qubes.vm.mix.net.NetVMMixin, qubes.vm.BaseVM):
         kwargs.setdefault('stdin', subprocess.PIPE)
         kwargs.setdefault('stdout', subprocess.PIPE)
         kwargs.setdefault('stderr', subprocess.PIPE)
+        if kwargs['stdin'] == subprocess.PIPE and input is None:
+            # workaround for https://bugs.python.org/issue39744
+            input = b''
         p = yield from self.run_service(*args, **kwargs)
 
         # this one is actually a tuple, but there is no need to unpack it
@@ -1471,6 +1474,9 @@ class QubesVM(qubes.vm.mix.net.NetVMMixin, qubes.vm.BaseVM):
         kwargs.setdefault('stdin', subprocess.PIPE)
         kwargs.setdefault('stdout', subprocess.PIPE)
         kwargs.setdefault('stderr', subprocess.PIPE)
+        if kwargs['stdin'] == subprocess.PIPE and input is None:
+            # workaround for https://bugs.python.org/issue39744
+            input = b''
         p = yield from self.run(*args, **kwargs)
         stdouterr = yield from p.communicate(input=input)