diff --git a/lib/jasmine-core/jasmine.js b/lib/jasmine-core/jasmine.js
index a15ad5ee..ac72688e 100644
--- a/lib/jasmine-core/jasmine.js
+++ b/lib/jasmine-core/jasmine.js
@@ -3492,10 +3492,9 @@ getJasmineRequireObj().CurrentRunableTracker = function() {
   return CurrentRunableTracker;
 };
 
-// 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$) {
+  'use strict';
+
   function DelayedFunctionScheduler() {
     this.scheduledLookup_ = [];
     this.scheduledFunctions_ = {};
@@ -3518,20 +3517,10 @@ getJasmineRequireObj().DelayedFunctionScheduler = function(j$) {
       timeoutKey,
       runAtMillis
     ) {
-      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.
-        j$.getEnv().deprecated(
-          "The eval form of setTimeout and setInterval is deprecated and will stop working in a future version of Jasmine's mock clock. Pass a function instead of a string."
+        throw new Error(
+          'The mock clock does not support the eval form of setTimeout and setInterval. Pass a function instead of a string.'
         );
-        f = function() {
-          // eslint-disable-next-line no-eval
-          return eval(funcToCall);
-        };
-      } else {
-        f = funcToCall;
       }
 
       millis = millis || 0;
@@ -3540,7 +3529,7 @@ getJasmineRequireObj().DelayedFunctionScheduler = function(j$) {
 
       const funcToSchedule = {
         runAtMillis: runAtMillis,
-        funcToCall: f,
+        funcToCall,
         recurring: recurring,
         params: params,
         timeoutKey: timeoutKey,
diff --git a/spec/core/DelayedFunctionSchedulerSpec.js b/spec/core/DelayedFunctionSchedulerSpec.js
index 9ff98c74..c7ea4a7c 100644
--- a/spec/core/DelayedFunctionSchedulerSpec.js
+++ b/spec/core/DelayedFunctionSchedulerSpec.js
@@ -1,4 +1,6 @@
 describe('DelayedFunctionScheduler', function() {
+  'use strict';
+  
   it('schedules a function for later execution', function() {
     const scheduler = new jasmineUnderTest.DelayedFunctionScheduler(),
       fn = jasmine.createSpy('fn');
@@ -12,21 +14,14 @@ describe('DelayedFunctionScheduler', function() {
     expect(fn).toHaveBeenCalled();
   });
 
-  it('schedules a string for later execution', function() {
-    const scheduler = new jasmineUnderTest.DelayedFunctionScheduler(),
-      strfn = 'horrible = true;';
-    spyOn(jasmineUnderTest.getEnv(), 'deprecated');
+  it('throws if a string is passed', function() {
+    const scheduler = new jasmineUnderTest.DelayedFunctionScheduler();
 
-    scheduler.scheduleFunction(strfn, 0);
-    expect(jasmineUnderTest.getEnv().deprecated).toHaveBeenCalledWith(
-      'The eval form of setTimeout and setInterval is deprecated and will ' +
-        "stop working in a future version of Jasmine's mock clock. Pass a " +
-        'function instead of a string.'
+    expect(function() {
+      scheduler.scheduleFunction('horrible = true;', 0);
+    }).toThrowError(
+      'The mock clock does not support the eval form of setTimeout and setInterval. Pass a function instead of a string.'
     );
-
-    scheduler.tick(0);
-
-    expect(horrible).toEqual(true);
   });
 
   it('#tick defaults to 0', function() {
diff --git a/src/core/DelayedFunctionScheduler.js b/src/core/DelayedFunctionScheduler.js
index abe157aa..b59c88cf 100644
--- a/src/core/DelayedFunctionScheduler.js
+++ b/src/core/DelayedFunctionScheduler.js
@@ -1,7 +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$) {
+  'use strict';
+
   function DelayedFunctionScheduler() {
     this.scheduledLookup_ = [];
     this.scheduledFunctions_ = {};
@@ -24,20 +23,10 @@ getJasmineRequireObj().DelayedFunctionScheduler = function(j$) {
       timeoutKey,
       runAtMillis
     ) {
-      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.
-        j$.getEnv().deprecated(
-          "The eval form of setTimeout and setInterval is deprecated and will stop working in a future version of Jasmine's mock clock. Pass a function instead of a string."
+        throw new Error(
+          'The mock clock does not support the eval form of setTimeout and setInterval. Pass a function instead of a string.'
         );
-        f = function() {
-          // eslint-disable-next-line no-eval
-          return eval(funcToCall);
-        };
-      } else {
-        f = funcToCall;
       }
 
       millis = millis || 0;
@@ -46,7 +35,7 @@ getJasmineRequireObj().DelayedFunctionScheduler = function(j$) {
 
       const funcToSchedule = {
         runAtMillis: runAtMillis,
-        funcToCall: f,
+        funcToCall,
         recurring: recurring,
         params: params,
         timeoutKey: timeoutKey,