diff --git a/pstack/skills/principle-fix-root-causes/SKILL.md b/pstack/skills/principle-fix-root-causes/SKILL.md
index 7e5a419ae..5291682d0 100644
--- a/pstack/skills/principle-fix-root-causes/SKILL.md
+++ b/pstack/skills/principle-fix-root-causes/SKILL.md
@@ -17,6 +17,7 @@ When debugging, do not fix symptoms. Trace every problem to its root cause and f
 - If a workaround needs a paragraph-long comment to justify it, the code is wrong (fix the code, not the comment)
 - Check for the pattern, not just the instance (grep for the same pattern, fix all instances)
 - When stuck, instrument. Don't guess (add logging, read the actual error)
+- If the deciding fact took a deep dig to find, propose the cheap, always-on signal that would have shown it at first look
 
 **Restart bugs: suspect state before code**