diff --git a/docker/__init__.py b/docker/__init__.py
index 03694ce6..3ff722bf 100644
--- a/docker/__init__.py
+++ b/docker/__init__.py
@@ -1 +1 @@
-from client import Client
\ No newline at end of file
+from .client import Client
diff --git a/docker/client.py b/docker/client.py
index 6443868b..fd9bed86 100644
--- a/docker/client.py
+++ b/docker/client.py
@@ -355,9 +355,9 @@ class BuilderClient(object):
         self.config['Image'] = self.image
         if id is None:
             cmd = self.config['Cmd']
-            self.config.Cmd = ['true']
+            self.config['Cmd'] = ['true']
             id = self.run()
-            self.config.Cmd = cmd
+            self.config['Cmd'] = cmd
 
         res = self.client.commit(id, author=self.maintainer)
         if 'Id' not in res: