diff --git a/SC2169.md b/SC2169.md
new file mode 100644
index 0000000..bd3a556
--- /dev/null
+++ b/SC2169.md
@@ -0,0 +1,5 @@
+## In dash, [\[ ]] is not supported.
+
+You are writing a script for `dash`, but you're using a feature that `dash` doesn't support (in this case, bash/ksh style `[[ .. ]]` conditions). 
+
+See Ubuntu's [DashAsBinSh](https://wiki.ubuntu.com/DashAsBinSh) migration guide for how to make bash-specific scripts dash-compatible.
\ No newline at end of file