diff --git a/dalle2_pytorch/dalle2_pytorch.py b/dalle2_pytorch/dalle2_pytorch.py
index 02734ea..ad39dfc 100644
--- a/dalle2_pytorch/dalle2_pytorch.py
+++ b/dalle2_pytorch/dalle2_pytorch.py
@@ -1,7 +1,7 @@
 import math
 from tqdm import tqdm
 from inspect import isfunction
-from functools import partial
+from functools import partial, wraps
 from contextlib import contextmanager
 from collections import namedtuple
 from pathlib import Path
@@ -45,6 +45,14 @@ def exists(val):
 def identity(t, *args, **kwargs):
     return t
 
+def maybe(fn):
+    @wraps(fn)
+    def inner(x):
+        if not exists(x):
+            return x
+        return fn(x)
+    return inner
+
 def default(val, d):
     if exists(val):
         return val
@@ -1844,6 +1852,8 @@ class Decoder(BaseGaussianDiffusion):
         b = shape[0]
         img = torch.randn(shape, device = device)
 
+        lowres_cond_img = maybe(normalize_neg_one_to_one)(lowres_cond_img)
+
         for i in tqdm(reversed(range(0, self.num_timesteps)), desc = 'sampling loop time step', total = self.num_timesteps):
             img = self.p_sample(
                 unet,
@@ -1868,9 +1878,7 @@ class Decoder(BaseGaussianDiffusion):
         # normalize to [-1, 1]
 
         x_start = normalize_neg_one_to_one(x_start)
-
-        if exists(lowres_cond_img):
-            lowres_cond_img = normalize_neg_one_to_one(lowres_cond_img)
+        lowres_cond_img = maybe(normalize_neg_one_to_one)(lowres_cond_img)
 
         # get x_t
 
diff --git a/setup.py b/setup.py
index a078830..4c9a312 100644
--- a/setup.py
+++ b/setup.py
@@ -10,7 +10,7 @@ setup(
       'dream = dalle2_pytorch.cli:dream'
     ],
   },
-  version = '0.2.16',
+  version = '0.2.17',
   license='MIT',
   description = 'DALL-E 2',
   author = 'Phil Wang',