diff --git a/runon/runon.py b/runon/runon.py
index 05120b0..89ade43 100755
--- a/runon/runon.py
+++ b/runon/runon.py
@@ -115,24 +115,15 @@ def build_image(client, conf, update, verbose):
         dockerfile.append(pkginstall.format(p))
     try:
         if verbose:
-            # fallback to external command 'docker build' as there is
-            # no way to follow the build progress with API.
             print('Building image {} ...'.format(tag))
-            cmd = ['docker', 'build']
-            if update:
-                cmd.append('--no-cache')
-            cmd += ['-t', tag, '-']
-            ret = subprocess.run(cmd,
-                                 input='\n'.join(dockerfile).encode('utf-8'),
-                                 stderr=subprocess.STDOUT, check=True)
-            image = client.images.get(tag)
-        else:
-            with io.BytesIO('\n'.join(dockerfile).encode('utf-8')) as fd:
-                image, logs = client.images.build(tag=tag, fileobj=fd, rm=True, nocache=update)
-            if verbose:
-                print('Built image {} / {}'.format(image.tags[0], image.short_id))
-                for l in logs:
-                    print(l.get('stream', '').strip('\n'))
+        cmd = ['docker', 'build']
+        if update:
+            cmd.append('--no-cache')
+        cmd += ['-t', tag, '-']
+        ret = subprocess.run(cmd,
+                             input='\n'.join(dockerfile).encode('utf-8'),
+                             stderr=subprocess.STDOUT, check=True)
+        image = client.images.get(tag)
 
         if not os.path.exists(cache_dir):
             os.mkdir(cache_dir)