diff --git a/src/PIL/Image.py b/src/PIL/Image.py
index c4ff94b6d..22ee46bfc 100644
--- a/src/PIL/Image.py
+++ b/src/PIL/Image.py
@@ -1725,6 +1725,8 @@ class Image(object):
         ):
             raise ValueError("unknown resampling filter")
 
+        size = tuple(size)
+
         if box is None:
             box = (0, 0) + self.size
         else: