diff --git a/javascript/ql/lib/semmle/javascript/security/dataflow/UnsafeHtmlConstructionQuery.qll b/javascript/ql/lib/semmle/javascript/security/dataflow/UnsafeHtmlConstructionQuery.qll
index 8e5060036af..cc98d4ece48 100644
--- a/javascript/ql/lib/semmle/javascript/security/dataflow/UnsafeHtmlConstructionQuery.qll
+++ b/javascript/ql/lib/semmle/javascript/security/dataflow/UnsafeHtmlConstructionQuery.qll
@@ -41,7 +41,6 @@ class Configration extends TaintTracking::Configuration {
   }
 
   override predicate isSanitizerGuard(TaintTracking::SanitizerGuardNode guard) {
-    guard instanceof PrefixStringSanitizer or
     guard instanceof QuoteGuard or
     guard instanceof ContainsHtmlGuard or
     guard instanceof TypeTestGuard
@@ -50,15 +49,6 @@ class Configration extends TaintTracking::Configuration {
 
 private import semmle.javascript.security.dataflow.Xss::Shared as Shared
 
-private class PrefixStringSanitizer extends TaintTracking::SanitizerGuardNode,
-  DomBasedXss::PrefixStringSanitizer {
-  PrefixStringSanitizer() { this = this }
-}
-
-private class PrefixString extends DataFlow::FlowLabel, DomBasedXss::PrefixString {
-  PrefixString() { this = this }
-}
-
 private class QuoteGuard extends TaintTracking::SanitizerGuardNode, Shared::QuoteGuard {
   QuoteGuard() { this = this }
 }