diff --git a/tools/rename-forth-to-retro.sh b/tools/rename-forth-to-retro.sh
new file mode 100755
index 0000000..4a620c6
--- /dev/null
+++ b/tools/rename-forth-to-retro.sh
@@ -0,0 +1,3 @@
+#!/bin/sh
+for f in *.forth; do mv -- "$f" "${f%.forth}.retro" ; done
+for f in *.retro; do fossil rename -- "${f%.retro}.forth" "$f" ; done