diff --git a/src/PIL/ImageFile.py b/src/PIL/ImageFile.py
index 69e7ee548..c8ad69f9b 100644
--- a/src/PIL/ImageFile.py
+++ b/src/PIL/ImageFile.py
@@ -206,6 +206,9 @@ class ImageFile(Image.Image):
         except AttributeError:
             seek = self.fp.seek
 
+        # XXX hack202406 disable unmodified code path
+        use_mmap = False
+
         if use_mmap:
             # try memory mapping
             decoder_name, extents, offset, args = self.tile[0]
diff --git a/src/_imaging.c b/src/_imaging.c
index ddc8d2885..caf02029d 100644
--- a/src/_imaging.c
+++ b/src/_imaging.c
@@ -96,7 +96,8 @@
 /* Configuration stuff. Feel free to undef things you don't need. */
 #define WITH_IMAGECHOPS  /* ImageChops support */
 #define WITH_IMAGEDRAW   /* ImageDraw support */
-#define WITH_MAPPING     /* use memory mapping to read some file formats */
+// XXX hack202406 disable unmodified code path
+// #define WITH_MAPPING     /* use memory mapping to read some file formats */
 #define WITH_IMAGEPATH   /* ImagePath stuff */
 #define WITH_ARROW       /* arrow graphics stuff (experimental) */
 #define WITH_EFFECTS     /* special effects */