diff --git a/map2map/data/fields.py b/map2map/data/fields.py
index d7224a8..16546ec 100644
--- a/map2map/data/fields.py
+++ b/map2map/data/fields.py
@@ -162,11 +162,9 @@ class FieldDataset(Dataset):
             if shift is not None:
                 anchor[d] += torch.randint(int(shift), (1,))
 
-        crop(in_fields, anchor, self.crop, self.in_pad, self.size)
+        crop(in_fields, anchor, self.crop, self.in_pad)
         crop(tgt_fields, anchor * self.scale_factor,
-             self.crop * self.scale_factor,
-             self.tgt_pad,
-             self.size * self.scale_factor)
+             self.crop * self.scale_factor, self.tgt_pad)
 
         style = torch.from_numpy(style).to(torch.float32)
         in_fields = [torch.from_numpy(f).to(torch.float32) for f in in_fields]
@@ -283,6 +281,7 @@ class FieldDataset(Dataset):
 
 def fill(field, patch, anchor):
     ndim = len(anchor)
+    assert field.ndim == patch.ndim == 1 + ndim, 'ndim mismatch'
 
     ind = [slice(None)]
     for d, (p, a, s) in enumerate(zip(
@@ -296,9 +295,11 @@ def fill(field, patch, anchor):
     field[ind] = patch
 
 
-def crop(fields, anchor, crop, pad, size):
+def crop(fields, anchor, crop, pad):
+    assert all(x.shape == fields[0].shape for x in fields), 'shape mismatch'
+    size = fields[0].shape[1:]
     ndim = len(size)
-    assert all(len(x) == ndim for x in [anchor, crop, pad]), 'ndim mismatch'
+    assert ndim == len(anchor) == len(crop) == len(pad), 'ndim mismatch'
 
     ind = [slice(None)]
     for d, (a, c, (p0, p1), s) in enumerate(zip(anchor, crop, pad, size)):