diff --git a/build/usr/lib/python3.6/lxcbuild/builder.py b/build/usr/lib/python3.6/lxcbuild/builder.py
index 4a64a76..3e20780 100644
--- a/build/usr/lib/python3.6/lxcbuild/builder.py
+++ b/build/usr/lib/python3.6/lxcbuild/builder.py
@@ -96,7 +96,7 @@ class Builder:
 
     def fix_layer(self, cmd):
         layers = [self.get_layer_path(layer) for layer in self.image.conf['layers']]
-        subprocess.run([cmd] + layers, check=True)
+        subprocess.run(cmd + layers, check=True)
 
     def copy_files(self, src, dst):
         dst = os.path.join(self.image.path, dst)
@@ -109,7 +109,7 @@ class Builder:
     def add_env(self, key, value):
         if 'env' not in self.image.conf:
             self.image.conf['env'] = []
-        self.image.conf['env'].append('{}={}'.format(key, value))
+        self.image.conf['env'].append([key, value])
 
     def set_user(self, uid, gid):
         self.image.conf['uid'] = uid