diff --git a/predict.py b/predict.py
index 9cfe187..20a75e4 100755
--- a/predict.py
+++ b/predict.py
@@ -49,7 +49,7 @@ def get_args():
     parser.add_argument('--model', '-m', default='MODEL.pth', metavar='FILE',
                         help='Specify the file in which the model is stored')
     parser.add_argument('--input', '-i', metavar='INPUT', nargs='+', help='Filenames of input images', required=True)
-    parser.add_argument('--output', '-o', metavar='INPUT', nargs='+', help='Filenames of output images')
+    parser.add_argument('--output', '-o', metavar='OUTPUT', nargs='+', help='Filenames of output images')
     parser.add_argument('--viz', '-v', action='store_true',
                         help='Visualize the images as they are processed')
     parser.add_argument('--no-save', '-n', action='store_true', help='Do not save the output masks')
diff --git a/utils/data_loading.py b/utils/data_loading.py
index 63c4313..e4625ac 100644
--- a/utils/data_loading.py
+++ b/utils/data_loading.py
@@ -64,7 +64,7 @@ class BasicDataset(Dataset):
         img = self.load(img_file[0])
 
         assert img.size == mask.size, \
-            'Image and mask {name} should be the same size, but are {img.size} and {mask.size}'
+            f'Image and mask {name} should be the same size, but are {img.size} and {mask.size}'
 
         img = self.preprocess(img, self.scale, is_mask=False)
         mask = self.preprocess(mask, self.scale, is_mask=True)