diff --git a/rules/S6606/javascript/rule.adoc b/rules/S6606/javascript/rule.adoc
index b13b798fdb..8c1c3dd00e 100644
--- a/rules/S6606/javascript/rule.adoc
+++ b/rules/S6606/javascript/rule.adoc
@@ -4,6 +4,8 @@ The nullish coalescing operator `??` allows providing a default value when deali
 
 This rule reports when disjunctions (`||`) and conditionals (`?`) can be safely replaced with coalescing (`??`).
 
+The TSConfig needs to set `strictNullChecks` to `true` for the rule to work properly.
+
 == How to fix it
 
 Rewrite the logical expression `||` using `??` on the unchecked operands.