diff --git a/src/PIL/ImageFile.py b/src/PIL/ImageFile.py
index 3390dfa97..78abe3c77 100644
--- a/src/PIL/ImageFile.py
+++ b/src/PIL/ImageFile.py
@@ -814,7 +814,7 @@ class PyCodec:
             self.state.ysize = y1 - y0
 
         if self.state.xsize <= 0 or self.state.ysize <= 0:
-            msg = "Size cannot be negative"
+            msg = "Size must be positive"
             raise ValueError(msg)
 
         if (