diff --git a/doc/ttoolfilter.lua b/doc/ttoolfilter.lua
new file mode 100644
index 0000000000000000000000000000000000000000..a02306abc7d5ffe2b93056002627ed78aa2ffb12
--- /dev/null
+++ b/doc/ttoolfilter.lua
@@ -0,0 +1,4 @@
+function Link(el)
+  el.target = string.gsub(el.target, "%.md", ".html")
+  return el
+end
\ No newline at end of file