diff --git a/torchvision/transforms/functional.py b/torchvision/transforms/functional.py
index c69ecb69d08..86bf361fcbb 100644
--- a/torchvision/transforms/functional.py
+++ b/torchvision/transforms/functional.py
@@ -117,7 +117,7 @@ def to_pil_image(pic, mode=None):
 
         elif pic.ndimension() == 2:
             # if 2D image, add channel dimension (CHW)
-            pic.unsqueeze_(0)
+            pic = pic.unsqueeze(0)
 
     elif isinstance(pic, np.ndarray):
         if pic.ndim not in {2, 3}: