diff --git a/torchvision/datasets/mnist.py b/torchvision/datasets/mnist.py
index 0467854e9b3..e191d70dd60 100644
--- a/torchvision/datasets/mnist.py
+++ b/torchvision/datasets/mnist.py
@@ -485,7 +485,7 @@ def read_sn3_pascalvincent_tensor(path: str, strict: bool = True) -> torch.Tenso
     """
     # read
     with open(path, "rb") as f:
-        data = f.read()
+        data = bytearray(f.read())
     # parse
     magic = get_int(data[0:4])
     nd = magic % 256