diff --git a/retag.sh b/retag.sh
new file mode 100755
index 0000000..b876e03
--- /dev/null
+++ b/retag.sh
@@ -0,0 +1,18 @@
+#!/usr/bin/env bash
+
+set -e
+
+first_commit=`git rev-list --max-parents=0 master`
+
+revs=`git rev-list --reverse ${first_commit}..master`
+
+git tag | xargs git tag -d
+
+for rev in $revs; do
+  message=`git log --pretty=tformat:%s -1  $rev`
+  chapter=`echo $message | sed -e "/^Chapter \(.*\):.*$/!d;s//ch\1/"`
+  if [[ -n $chapter ]]; then
+    git tag $chapter $rev
+  fi
+done
+