diff --git a/src/PIL/IcoImagePlugin.py b/src/PIL/IcoImagePlugin.py
index dc2d6606a..152d2a275 100644
--- a/src/PIL/IcoImagePlugin.py
+++ b/src/PIL/IcoImagePlugin.py
@@ -52,7 +52,7 @@ def _save(im, fp, filename):
     sizes = list(sizes)
     fp.write(struct.pack("<H", len(sizes)))  # idCount(2)
     offset = fp.tell() + len(sizes) * 16
-    alt_images = {im.size: im for im in im.encoderinfo.get("append_images", [])}
+    provided_images = {im.size: im for im in im.encoderinfo.get("append_images", [])}
     for size in sizes:
         width, height = size
         # 0 means 256
@@ -64,7 +64,7 @@ def _save(im, fp, filename):
         fp.write(struct.pack("<H", 32))  # wBitCount(2)
 
         image_io = BytesIO()
-        tmp = alt_images.get(size)
+        tmp = provided_images.get(size)
         if not tmp:
             # TODO: invent a more convenient method for proportional scalings
             tmp = im.copy()