diff --git a/cliff/complete.py b/cliff/complete.py
index bb5ef28..c84f0ca 100644
--- a/cliff/complete.py
+++ b/cliff/complete.py
@@ -21,9 +21,21 @@ class CompleteDictionary:
         optstr = ' '.join(opt for action in actions
                           for opt in action.option_strings)
         dicto = self._dictionary
+        last_cmd = command[-1]
         for subcmd in command[:-1]:
-            dicto = dicto.setdefault(subcmd, {})
-        dicto[command[-1]] = optstr
+            subdata = dicto.get(subcmd)
+            # If there is a string in corresponding dictionary, it means the
+            # verb used for the command exists already.
+            # For example, {'cmd': 'action'}, and we add the command
+            # 'cmd_other'. We want the result to be
+            # {'cmd': 'action other', 'cmd_other': 'sub_action'}
+            if isinstance(subdata, six.string_types):
+                subdata += ' ' + last_cmd
+                dicto[subcmd] = subdata
+                last_cmd = subcmd + '_' + last_cmd
+            else:
+                dicto = dicto.setdefault(subcmd, {})
+        dicto[last_cmd] = optstr
 
     def get_commands(self):
         return ' '.join(k for k in sorted(self._dictionary.keys()))
diff --git a/cliff/tests/test_complete.py b/cliff/tests/test_complete.py
index 441b2ff..6134f57 100644
--- a/cliff/tests/test_complete.py
+++ b/cliff/tests/test_complete.py
@@ -32,6 +32,26 @@ def test_complete_dictionary():
     assert "2" == result[3][1]
 
 
+def test_complete_dictionary_subcmd():
+    sot = complete.CompleteDictionary()
+    sot.add_command("image delete".split(),
+                    [mock.Mock(option_strings=["1"])])
+    sot.add_command("image list".split(),
+                    [mock.Mock(option_strings=["2"])])
+    sot.add_command("image list better".split(),
+                    [mock.Mock(option_strings=["3"])])
+    assert "image" == sot.get_commands()
+    result = sot.get_data()
+    assert "image" == result[0][0]
+    assert "delete list list_better" == result[0][1]
+    assert "image_delete" == result[1][0]
+    assert "1" == result[1][1]
+    assert "image_list" == result[2][0]
+    assert "2 better" == result[2][1]
+    assert "image_list_better" == result[3][0]
+    assert "3" == result[3][1]
+
+
 class FakeStdout:
     def __init__(self):
         self.content = []