diff --git a/tests/qemu-iotests/206 b/tests/qemu-iotests/206
index e92550fa59..5bb738bf23 100755
--- a/tests/qemu-iotests/206
+++ b/tests/qemu-iotests/206
@@ -27,7 +27,7 @@ iotests.verify_image_format(supported_fmts=['qcow2'])
 
 def blockdev_create(vm, options):
     result = vm.qmp_log('blockdev-create',
-                        filters=[iotests.filter_testfiles],
+                        filters=[iotests.filter_qmp_testfiles],
                         job_id='job0', options=options)
 
     if 'return' in result:
@@ -55,7 +55,7 @@ with iotests.FilePath('t.qcow2') as disk_path, \
                           'size': 0 })
 
     vm.qmp_log('blockdev-add',
-               filters=[iotests.filter_testfiles],
+               filters=[iotests.filter_qmp_testfiles],
                driver='file', filename=disk_path,
                node_name='imgfile')
 
diff --git a/tests/qemu-iotests/iotests.py b/tests/qemu-iotests/iotests.py
index 57fe20db45..a96a7010d4 100644
--- a/tests/qemu-iotests/iotests.py
+++ b/tests/qemu-iotests/iotests.py
@@ -246,10 +246,33 @@ def filter_qmp_event(event):
         event['timestamp']['microseconds'] = 'USECS'
     return event
 
+def filter_qmp(qmsg, filter_fn):
+    '''Given a string filter, filter a QMP object's values.
+    filter_fn takes a (key, value) pair.'''
+    # Iterate through either lists or dicts;
+    if isinstance(qmsg, list):
+        items = enumerate(qmsg)
+    else:
+        items = qmsg.items()
+
+    for k, v in items:
+        if isinstance(v, list) or isinstance(v, dict):
+            qmsg[k] = filter_qmp(v, filter_fn)
+        else:
+            qmsg[k] = filter_fn(k, v)
+    return qmsg
+
 def filter_testfiles(msg):
     prefix = os.path.join(test_dir, "%s-" % (os.getpid()))
     return msg.replace(prefix, 'TEST_DIR/PID-')
 
+def filter_qmp_testfiles(qmsg):
+    def _filter(key, value):
+        if key == 'filename' or key == 'backing-file':
+            return filter_testfiles(value)
+        return value
+    return filter_qmp(qmsg, _filter)
+
 def filter_generated_node_ids(msg):
     return re.sub("#block[0-9]+", "NODE_NAME", msg)
 
@@ -465,10 +488,9 @@ class VM(qtest.QEMUQtestMachine):
             ("execute", cmd),
             ("arguments", ordered_kwargs(kwargs))
         ))
-        logmsg = json.dumps(full_cmd)
-        log(logmsg, filters)
+        log(full_cmd, filters)
         result = self.qmp(cmd, **kwargs)
-        log(json.dumps(result, sort_keys=True), filters)
+        log(result, filters)
         return result
 
     def run_job(self, job, auto_finalize=True, auto_dismiss=False):