diff --git a/src/js/resources/prevent-settimeout.js b/src/js/resources/prevent-settimeout.js
index c137f0dc7..289c44659 100644
--- a/src/js/resources/prevent-settimeout.js
+++ b/src/js/resources/prevent-settimeout.js
@@ -95,8 +95,8 @@ export function preventSetTimeout(
     proxyApplyFn('setTimeout', function(context) {
         const { callArgs } = context;
         const a = callArgs[0] instanceof Function
-            ? String(safe.Function_toString(callArgs[0]))
-            : String(callArgs[0]);
+            ? safe.String(safe.Function_toString(callArgs[0]))
+            : safe.String(callArgs[0]);
         const b = callArgs[1];
         if ( needleRaw === '' && range.unbound() ) {
             safe.uboLog(logPrefix, `Called:\n${a}\n${b}`);
@@ -159,8 +159,8 @@ export function preventSetInterval(
     proxyApplyFn('setInterval', function(context) {
         const { callArgs } = context;
         const a = callArgs[0] instanceof Function
-            ? String(safe.Function_toString(callArgs[0]))
-            : String(callArgs[0]);
+            ? safe.String(safe.Function_toString(callArgs[0]))
+            : safe.String(callArgs[0]);
         const b = callArgs[1];
         if ( needleRaw === '' && range.unbound() ) {
             safe.uboLog(logPrefix, `Called:\n${a}\n${b}`);
@@ -212,8 +212,8 @@ export function preventRequestAnimationFrame(
     proxyApplyFn('requestAnimationFrame', function(context) {
         const { callArgs } = context;
         const a = callArgs[0] instanceof Function
-            ? String(safe.Function_toString(callArgs[0]))
-            : String(callArgs[0]);
+            ? safe.String(safe.Function_toString(callArgs[0]))
+            : safe.String(callArgs[0]);
         if ( needleRaw === '' ) {
             safe.uboLog(logPrefix, `Called:\n${a}`);
         } else if ( reNeedle.test(a) !== needleNot ) {
diff --git a/src/js/resources/safe-self.js b/src/js/resources/safe-self.js
index 3766f3e19..6b6d72eeb 100644
--- a/src/js/resources/safe-self.js
+++ b/src/js/resources/safe-self.js
@@ -50,6 +50,7 @@ export function safeSelf() {
         'RegExp_test': self.RegExp.prototype.test,
         'RegExp_exec': self.RegExp.prototype.exec,
         'Request_clone': self.Request.prototype.clone,
+        'String': self.String,
         'String_fromCharCode': String.fromCharCode,
         'String_split': String.prototype.split,
         'XMLHttpRequest': self.XMLHttpRequest,