diff --git a/ext/.document b/ext/.document
new file mode 100644
index 0000000000..797d8dcef8
--- /dev/null
+++ b/ext/.document
@@ -0,0 +1,5 @@
+# Add files to this as they become documented
+
+iconv/iconv.c
+strscan/strscan.c
+zlib/zlib.c