diff --git a/demo.py b/demo.py
index 259a07a..a4371ad 100644
--- a/demo.py
+++ b/demo.py
@@ -39,13 +39,14 @@ def main(args):
         device=args.device
     )
     image = engine(
-        prompt=args.prompt,
-        init_image=None if args.init_image is None else cv2.imread(args.init_image),
-        mask=None if args.mask is None else cv2.imread(args.mask, 0),
-        strength=args.strength,
-        num_inference_steps=args.num_inference_steps,
-        guidance_scale=args.guidance_scale,
-        eta=args.eta
+        prompt = args.prompt,
+        init_image = None if args.init_image is None else cv2.imread(args.init_image),
+        mask = None if args.mask is None else cv2.imread(args.mask, 0),
+        strength = args.strength,
+        num_inference_steps = args.num_inference_steps,
+        guidance_scale = args.guidance_scale,
+        eta = args.eta,
+        unprompt = args.unprompt
     )
     cv2.imwrite(args.output, image)
 
@@ -79,5 +80,7 @@ def main(args):
     parser.add_argument("--mask", type=str, default=None, help="mask of the region to inpaint on the initial image")
     # output name
     parser.add_argument("--output", type=str, default="output.png", help="output image name")
+    # unprompt
+    parser.add_argument("--unprompt", type=str, default="", help="negative prompt")
     args = parser.parse_args()
     main(args)
diff --git a/stable_diffusion_engine.py b/stable_diffusion_engine.py
index 98fc88d..3e6468d 100644
--- a/stable_diffusion_engine.py
+++ b/stable_diffusion_engine.py
@@ -106,7 +106,8 @@ def __call__(
             strength = 0.5,
             num_inference_steps = 32,
             guidance_scale = 7.5,
-            eta = 0.0
+            eta = 0.0,
+            unprompt = ""
     ):
         # extract condition
         tokens = self.tokenizer(
@@ -122,7 +123,7 @@ def __call__(
         # do classifier free guidance
         if guidance_scale > 1.0:
             tokens_uncond = self.tokenizer(
-                "",
+                unprompt,
                 padding="max_length",
                 max_length=self.tokenizer.model_max_length,
                 truncation=True