diff --git a/torchvision/transforms/functional.py b/torchvision/transforms/functional.py
index b5c242c1e64..6578f6c1c67 100644
--- a/torchvision/transforms/functional.py
+++ b/torchvision/transforms/functional.py
@@ -8,6 +8,7 @@
 import numpy as np
 import torch
 from PIL import Image
+from PIL.Image import Image as PILImage
 from torch import Tensor
 
 try:
@@ -123,7 +124,7 @@ def _is_numpy_image(img: Any) -> bool:
     return img.ndim in {2, 3}
 
 
-def to_tensor(pic) -> Tensor:
+def to_tensor(pic: Union[PILImage, np.ndarray]) -> Tensor:
     """Convert a ``PIL Image`` or ``numpy.ndarray`` to tensor.
     This function does not support torchscript.