diff --git a/img2img.py b/img2img.py
index 7440db3..84e31dd 100644
--- a/img2img.py
+++ b/img2img.py
@@ -12,6 +12,12 @@
     help="the prompt to render",
 )
 
+parser.add_argument(
+    "--negative-prompt",
+    type=str,
+    help="the negative prompt to use (if any)",
+)
+
 parser.add_argument(
     "--steps", 
     type=int, 
@@ -45,6 +51,7 @@
 
 img = generator.generate(
     args.prompt,
+    negative_prompt=args.negative_prompt,
     num_steps=args.steps,
     unconditional_guidance_scale=7.5,
     temperature=1,
diff --git a/stable_diffusion_tf/stable_diffusion.py b/stable_diffusion_tf/stable_diffusion.py
index c7b772c..ef215cc 100644
--- a/stable_diffusion_tf/stable_diffusion.py
+++ b/stable_diffusion_tf/stable_diffusion.py
@@ -40,6 +40,7 @@ def __init__(self, img_height=1000, img_width=1000, jit_compile=False, download_
     def generate(
         self,
         prompt,
+        negative_prompt=None,
         batch_size=1,
         num_steps=25,
         unconditional_guidance_scale=7.5,
@@ -85,13 +86,19 @@ def generate(
             latent_mask_tensor = tf.cast(tf.repeat(latent_mask, batch_size , axis=0), self.dtype)
 
 
+        # Tokenize negative prompt or use default padding tokens
+        unconditional_tokens = _UNCONDITIONAL_TOKENS
+        if negative_prompt is not None:
+            inputs = self.tokenizer.encode(negative_prompt)
+            assert len(inputs) < 77, "Negative prompt is too long (should be < 77 tokens)"
+            unconditional_tokens = inputs + [49407] * (77 - len(inputs))
+
         # Encode unconditional tokens (and their positions into an
         # "unconditional context vector"
-        unconditional_tokens = np.array(_UNCONDITIONAL_TOKENS)[None].astype("int32")
+        unconditional_tokens = np.array(unconditional_tokens)[None].astype("int32")
         unconditional_tokens = np.repeat(unconditional_tokens, batch_size, axis=0)
-        self.unconditional_tokens = tf.convert_to_tensor(unconditional_tokens)
         unconditional_context = self.text_encoder.predict_on_batch(
-            [self.unconditional_tokens, pos_ids]
+            [unconditional_tokens, pos_ids]
         )
         timesteps = np.arange(1, 1000, 1000 // num_steps)
         input_img_noise_t = timesteps[ int(len(timesteps)*input_image_strength) ]
@@ -146,9 +153,10 @@ def timestep_embedding(self, timesteps, dim=320, max_period=10000):
         embedding = np.concatenate([np.cos(args), np.sin(args)])
         return tf.convert_to_tensor(embedding.reshape(1, -1),dtype=self.dtype)
 
-    def add_noise(self, x , t ):
+    def add_noise(self, x , t , noise=None ):
         batch_size,w,h = x.shape[0] , x.shape[1] , x.shape[2]
-        noise = tf.random.normal((batch_size,w,h,4), dtype=self.dtype)
+        if noise is None:
+            noise = tf.random.normal((batch_size,w,h,4), dtype=self.dtype)
         sqrt_alpha_prod = _ALPHAS_CUMPROD[t] ** 0.5
         sqrt_one_minus_alpha_prod = (1 - _ALPHAS_CUMPROD[t]) ** 0.5
 
diff --git a/text2image.py b/text2image.py
index b85b3f8..4e19b53 100644
--- a/text2image.py
+++ b/text2image.py
@@ -13,6 +13,12 @@
     help="the prompt to render",
 )
 
+parser.add_argument(
+    "--negative-prompt",
+    type=str,
+    help="the negative prompt to use (if any)",
+)
+
 parser.add_argument(
     "--output",
     type=str,
@@ -68,6 +74,7 @@
 generator = StableDiffusion(img_height=args.H, img_width=args.W, jit_compile=False)
 img = generator.generate(
     args.prompt,
+    negative_prompt=args.negative_prompt,
     num_steps=args.steps,
     unconditional_guidance_scale=args.scale,
     temperature=1,