diff --git a/options/test_options.py b/options/test_options.py
index 6b79860fd50..d73ab32d121 100644
--- a/options/test_options.py
+++ b/options/test_options.py
@@ -10,4 +10,5 @@ def initialize(self):
         self.parser.add_argument('--phase', type=str, default='test', help='train, val, test, etc')
         self.parser.add_argument('--which_epoch', type=str, default='latest', help='which epoch to load? set to latest to use latest cached model')
         self.parser.add_argument('--how_many', type=int, default=50, help='how many test images to run')
+        self.parser.add_argument('--identity', type=float, default=0.0, help='use identity mapping. Setting identity other than 1 has an effect of scaling the weight of the identity mapping loss. For example, if the weight of the identity loss should be 10 times smaller than the weight of the reconstruction loss, please set optidentity = 0.1')
         self.isTrain = False