diff --git a/Data-structure-survey.md b/Data-structure-survey.md
index c7b8c8d..fc4d379 100644
--- a/Data-structure-survey.md
+++ b/Data-structure-survey.md
@@ -110,7 +110,8 @@ Hash table
 
     For the zones table, `catz` goes wrong if the `zone{}` clause does not
     state the zone's name in all lower-case; the case of the zone name in the
-    `catalog-zones{}` clause does not matter.
+    `catalog-zones{}` clause does not matter. Initializing the hash table as
+    case-insensitive is not enough to fix this bug.
 
   * `dns/rpz`