diff --git a/man4/loop.4 b/man4/loop.4
index 33e5b4199..84df76da4 100644
--- a/man4/loop.4
+++ b/man4/loop.4
@@ -136,6 +136,14 @@ The (third)
 argument must be a pointer to a
 .IR "struct loop_info" .
 .TP
+.BR LOOP_CHANGE_FD " (since Linux 2.6.5)"
+Switch the backing store of the loop device to the new file identified
+file descriptor specified in the (third)
+.BR ioctl (2)
+argument, which is an integer.
+This operation is possible only if the loop device is read-only and
+the new backing store is the same size and type as the old backing store.
+.TP
 .BR LOOP_SET_CAPACITY " (since Linux 2.6.30)"
 .\" commit 53d6660836f233df66490707365ab177e5fb2bb4
 Resize a live loop device.