diff --git a/tests/qemu-iotests/040 b/tests/qemu-iotests/040
index 5601a4873c..e61e7f2433 100755
--- a/tests/qemu-iotests/040
+++ b/tests/qemu-iotests/040
@@ -62,9 +62,10 @@ class ImageCommitTestCase(iotests.QMPTestCase):
         self.assert_no_active_block_jobs()
         if node_names:
             result = self.vm.qmp('block-commit', device='drive0', top_node=top, base_node=base)
+            self.assert_qmp(result, 'return', {})
         else:
             result = self.vm.qmp('block-commit', device='drive0', top=top, base=base)
-        self.assert_qmp(result, 'return', {})
+            self.assert_qmp(result, 'return', {})
         self.wait_for_complete(need_ready)
 
     def run_default_commit_test(self):
diff --git a/tests/qemu-iotests/147 b/tests/qemu-iotests/147
index 47dfa62e6b..770b73e2f4 100755
--- a/tests/qemu-iotests/147
+++ b/tests/qemu-iotests/147
@@ -159,10 +159,11 @@ class BuiltinNBD(NBDBlockdevAddBase):
 
         if export_name is None:
             result = self.server.qmp('nbd-server-add', device='nbd-export')
+            self.assert_qmp(result, 'return', {})
         else:
             result = self.server.qmp('nbd-server-add', device='nbd-export',
                                      name=export_name)
-        self.assert_qmp(result, 'return', {})
+            self.assert_qmp(result, 'return', {})
 
         if export_name2 is not None:
             result = self.server.qmp('nbd-server-add', device='nbd-export',
diff --git a/tests/qemu-iotests/155 b/tests/qemu-iotests/155
index eadda52615..d3e1b7401e 100755
--- a/tests/qemu-iotests/155
+++ b/tests/qemu-iotests/155
@@ -181,6 +181,7 @@ class MirrorBaseClass(BaseClass):
             result = self.vm.qmp(self.cmd, job_id='mirror-job', device='source',
                                  sync=sync, target='target',
                                  auto_finalize=False)
+            self.assert_qmp(result, 'return', {})
         else:
             if self.existing:
                 mode = 'existing'
@@ -190,8 +191,7 @@ class MirrorBaseClass(BaseClass):
                                  sync=sync, target=target_img,
                                  format=iotests.imgfmt, mode=mode,
                                  node_name='target', auto_finalize=False)
-
-        self.assert_qmp(result, 'return', {})
+            self.assert_qmp(result, 'return', {})
 
         self.vm.run_job('mirror-job', auto_finalize=False,
                         pre_finalize=self.openBacking, auto_dismiss=True)
diff --git a/tests/qemu-iotests/218 b/tests/qemu-iotests/218
index 6320c4cb56..5e74c55b6a 100755
--- a/tests/qemu-iotests/218
+++ b/tests/qemu-iotests/218
@@ -61,14 +61,14 @@ def start_mirror(vm, speed=None, buf_size=None):
                          sync='full',
                          speed=speed,
                          buf_size=buf_size)
+        assert ret['return'] == {}
     else:
         ret = vm.qmp('blockdev-mirror',
                          job_id='mirror',
                          device='source',
                          target='target',
                          sync='full')
-
-    assert ret['return'] == {}
+        assert ret['return'] == {}
 
 
 log('')
diff --git a/tests/qemu-iotests/296 b/tests/qemu-iotests/296
index 0d21b740a7..19a674c5ae 100755
--- a/tests/qemu-iotests/296
+++ b/tests/qemu-iotests/296
@@ -133,9 +133,10 @@ class EncryptionSetupTestCase(iotests.QMPTestCase):
 
         if reOpen:
             result = vm.qmp(command, options=[opts])
+            self.assert_qmp(result, 'return', {})
         else:
             result = vm.qmp(command, **opts)
-        self.assert_qmp(result, 'return', {})
+            self.assert_qmp(result, 'return', {})
 
 
     ###########################################################################