diff --git a/PIL/PixarImagePlugin.py b/PIL/PixarImagePlugin.py
index db2ee55f8..783462a9a 100644
--- a/PIL/PixarImagePlugin.py
+++ b/PIL/PixarImagePlugin.py
@@ -64,5 +64,4 @@ class PixarImageFile(ImageFile.ImageFile):
 
 Image.register_open(PixarImageFile.format, PixarImageFile)
 
-#
-# FIXME: what's the standard extension?
+Image.register_extension(PixarImageFile.format, ".pxr")