diff --git a/lib/jasmine-core/jasmine.js b/lib/jasmine-core/jasmine.js
index 6939bd8f..67e5424f 100644
--- a/lib/jasmine-core/jasmine.js
+++ b/lib/jasmine-core/jasmine.js
@@ -3224,6 +3224,9 @@ getJasmineRequireObj().CompleteOnFirstErrorSkipPolicy = function(j$) {
   return CompleteOnFirstErrorSkipPolicy;
 };
 
+// Warning: don't add "use strict" to this file. Doing so potentially changes
+// the behavior of user code that does things like setTimeout("var x = 1;")
+// while the mock clock is installed.
 getJasmineRequireObj().DelayedFunctionScheduler = function(j$) {
   function DelayedFunctionScheduler() {
     this.scheduledLookup_ = [];
@@ -3249,6 +3252,9 @@ getJasmineRequireObj().DelayedFunctionScheduler = function(j$) {
     ) {
       let f;
       if (typeof funcToCall === 'string') {
+        // setTimeout("some code") and setInterval("some code") are legal, if
+        // not recommended. We don't do that ourselves, but user code might.
+        // This allows such code to work when the mock clock is installed.
         f = function() {
           // eslint-disable-next-line no-eval
           return eval(funcToCall);
diff --git a/src/core/DelayedFunctionScheduler.js b/src/core/DelayedFunctionScheduler.js
index ef2c2f4f..9ea6c5f3 100644
--- a/src/core/DelayedFunctionScheduler.js
+++ b/src/core/DelayedFunctionScheduler.js
@@ -1,3 +1,6 @@
+// Warning: don't add "use strict" to this file. Doing so potentially changes
+// the behavior of user code that does things like setTimeout("var x = 1;")
+// while the mock clock is installed.
 getJasmineRequireObj().DelayedFunctionScheduler = function(j$) {
   function DelayedFunctionScheduler() {
     this.scheduledLookup_ = [];
@@ -23,6 +26,9 @@ getJasmineRequireObj().DelayedFunctionScheduler = function(j$) {
     ) {
       let f;
       if (typeof funcToCall === 'string') {
+        // setTimeout("some code") and setInterval("some code") are legal, if
+        // not recommended. We don't do that ourselves, but user code might.
+        // This allows such code to work when the mock clock is installed.
         f = function() {
           // eslint-disable-next-line no-eval
           return eval(funcToCall);