diff --git a/devtools/bolt-catchup.sh b/devtools/bolt-catchup.sh
new file mode 100755
index 000000000..60f5662e5
--- /dev/null
+++ b/devtools/bolt-catchup.sh
@@ -0,0 +1,25 @@
+#! /bin/sh
+# A script to upgrade spec versions one at a time, stop when something changes.
+
+set -e
+BOLTDIR=${1:-../bolts}
+
+HEAD=$(git -C "$BOLTDIR" show --format=%H -s)
+VERSION=$(sed -n 's/^DEFAULT_BOLTVERSION[ ]*:=[ ]*\([0-9a-f]*\)/\1/p' < Makefile)
+
+# We only change Makefile at exit, otherwise git diff shows the difference, of course!
+finalize_and_exit()
+{
+    sed "s/^DEFAULT_BOLTVERSION[ ]*:=[ ]*\([0-9a-f]*\)/DEFAULT_BOLTVERSION := $v/" < Makefile > Makefile.$$ && mv Makefile.$$ Makefile
+    exit 0
+}
+
+for v in $(git -C "$BOLTDIR" show "$VERSION..$HEAD" --format=%H -s | tac); do
+    echo "Trying $v..."
+    make -s extract-bolt-csv DEFAULT_BOLTVERSION="$v" || finalize_and_exit
+    git diff --exit-code || finalize_and_exit
+    make -s check-source-bolt DEFAULT_BOLTVERSION="$v" || finalize_and_exit
+done
+
+echo "No changes, simply upgrading to $v..."
+finalize_and_exit