diff --git a/app/lib/world/script_event_prereqs.coffee b/app/lib/world/script_event_prereqs.coffee
index 25b1dc47d..fa250f7ce 100644
--- a/app/lib/world/script_event_prereqs.coffee
+++ b/app/lib/world/script_event_prereqs.coffee
@@ -10,7 +10,7 @@ module.exports.scriptMatchesEventPrereqs = scriptMatchesEventPrereqs = (script,
     return false if ap.greaterThanOrEqualTo? and not (v >= ap.greaterThanOrEqualTo)
     return false if ap.lessThan? and not (v < ap.lessThan)
     return false if ap.lessThanOrEqualTo? and not (v <= ap.lessThanOrEqualTo)
-    return false if ap.containingString? and v.search(ap.containingString) == -1
-    return false if ap.notContainingString? and v.search(ap.containingString) != -1
+    return false if ap.containingString? and v?.search(ap.containingString) == -1
+    return false if ap.notContainingString? and v?.search(ap.containingString) != -1
 
   return true