diff --git a/src/internal/observable/dom/AjaxObservable.ts b/src/internal/observable/dom/AjaxObservable.ts
index cedfb3a60c..e258e6ddc7 100644
--- a/src/internal/observable/dom/AjaxObservable.ts
+++ b/src/internal/observable/dom/AjaxObservable.ts
@@ -461,7 +461,7 @@ export type AjaxErrorNames = 'AjaxError' | 'AjaxTimeoutError';
  *
  * @class AjaxError
  */
-export class AjaxError extends Error {
+export interface AjaxError extends Error {
   /** @type {XMLHttpRequest} The XHR instance associated with the error */
   xhr: XMLHttpRequest;
 
@@ -476,22 +476,28 @@ export class AjaxError extends Error {
 
   /** @type {string|ArrayBuffer|Document|object|any} The response data */
   response: any;
+}
 
-  public readonly name: AjaxErrorNames = 'AjaxError';
-
-  constructor(message: string, xhr: XMLHttpRequest, request: AjaxRequest) {
-    super(message);
-    this.message = message;
-    this.xhr = xhr;
-    this.request = request;
-    this.status = xhr.status;
-    this.responseType = xhr.responseType || request.responseType;
-    this.response = parseXhrResponse(this.responseType, xhr);
+export interface AjaxErrorCtor {
+  new(message: string, xhr: XMLHttpRequest, request: AjaxRequest): AjaxError;
+}
 
-    (Object as any).setPrototypeOf(this, AjaxError.prototype);
-  }
+function AjaxErrorImpl(this: any, message: string, xhr: XMLHttpRequest, request: AjaxRequest): AjaxError {
+  Error.call(this);
+  this.message = message;
+  this.name = 'AjaxError';
+  this.xhr = xhr;
+  this.request = request;
+  this.status = xhr.status;
+  this.responseType = xhr.responseType || request.responseType;
+  this.response = parseXhrResponse(this.responseType, xhr);
+  return this;
 }
 
+AjaxErrorImpl.prototype = Object.create(Error.prototype);
+
+export const AjaxError: AjaxErrorCtor = AjaxErrorImpl as any;
+
 function parseJson(xhr: XMLHttpRequest) {
   // HACK(benlesh): TypeScript shennanigans
   // tslint:disable-next-line:no-any XMLHttpRequest is defined to always have 'response' inferring xhr as never for the else clause.
@@ -517,17 +523,22 @@ function parseXhrResponse(responseType: string, xhr: XMLHttpRequest) {
   }
 }
 
+export interface AjaxTimeoutError extends AjaxError {
+}
+
+export interface AjaxTimeoutErrorCtor {
+  new(xhr: XMLHttpRequest, request: AjaxRequest): AjaxTimeoutError;
+}
+
+function AjaxTimeoutErrorImpl(this: any, xhr: XMLHttpRequest, request: AjaxRequest) {
+  AjaxError.call(this, 'ajax timeout', xhr, request);
+  this.name = 'AjaxTimeoutError';
+  return this;
+}
+
 /**
  * @see {@link ajax}
  *
  * @class AjaxTimeoutError
  */
-export class AjaxTimeoutError extends AjaxError {
-
-  public readonly name: AjaxErrorNames = 'AjaxTimeoutError';
-
-  constructor(xhr: XMLHttpRequest, request: AjaxRequest) {
-    super('ajax timeout', xhr, request);
-    (Object as any).setPrototypeOf(this, AjaxTimeoutError.prototype);
-  }
-}
+export const AjaxTimeoutError: AjaxTimeoutErrorCtor = AjaxTimeoutErrorImpl as any;
diff --git a/src/internal/util/ArgumentOutOfRangeError.ts b/src/internal/util/ArgumentOutOfRangeError.ts
index 90cd3324e3..949bfcc9da 100644
--- a/src/internal/util/ArgumentOutOfRangeError.ts
+++ b/src/internal/util/ArgumentOutOfRangeError.ts
@@ -1,3 +1,19 @@
+export interface ArgumentOutOfRangeError extends Error {
+}
+
+export interface ArgumentOutOfRangeErrorCtor {
+  new(): ArgumentOutOfRangeError;
+}
+
+function ArgumentOutOfRangeErrorImpl(this: any) {
+  Error.call(this);
+  this.message = 'argument out of range';
+  this.name = 'ArgumentOutOfRangeError';
+  return this;
+}
+
+ArgumentOutOfRangeErrorImpl.prototype = Object.create(Error.prototype);
+
 /**
  * An error thrown when an element was queried at a certain index of an
  * Observable, but no such index or position exists in that sequence.
@@ -8,12 +24,4 @@
  *
  * @class ArgumentOutOfRangeError
  */
-export class ArgumentOutOfRangeError extends Error {
-
-  public readonly name = 'ArgumentOutOfRangeError';
-
-  constructor() {
-    super('argument out of range');
-    (Object as any).setPrototypeOf(this, ArgumentOutOfRangeError.prototype);
-  }
-}
+export const ArgumentOutOfRangeError: ArgumentOutOfRangeErrorCtor = ArgumentOutOfRangeErrorImpl as any;
\ No newline at end of file
diff --git a/src/internal/util/EmptyError.ts b/src/internal/util/EmptyError.ts
index 743e43dafb..6dacfc6aa8 100644
--- a/src/internal/util/EmptyError.ts
+++ b/src/internal/util/EmptyError.ts
@@ -1,3 +1,19 @@
+export interface EmptyError extends Error {
+}
+
+export interface EmptyErrorCtor {
+  new(): EmptyError;
+}
+
+function EmptyErrorImpl(this: any) {
+  Error.call(this);
+  this.message = 'no elements in sequence';
+  this.name = 'EmptyError';
+  return this;
+}
+
+EmptyErrorImpl.prototype = Object.create(Error.prototype);
+
 /**
  * An error thrown when an Observable or a sequence was queried but has no
  * elements.
@@ -8,12 +24,4 @@
  *
  * @class EmptyError
  */
-export class EmptyError extends Error {
-
-  public readonly name = 'EmptyError';
-
-  constructor() {
-    super('no elements in sequence');
-    (Object as any).setPrototypeOf(this, EmptyError.prototype);
-  }
-}
+export const EmptyError: EmptyErrorCtor = EmptyErrorImpl as any;
\ No newline at end of file
diff --git a/src/internal/util/ObjectUnsubscribedError.ts b/src/internal/util/ObjectUnsubscribedError.ts
index 3c694a48be..e068c54347 100644
--- a/src/internal/util/ObjectUnsubscribedError.ts
+++ b/src/internal/util/ObjectUnsubscribedError.ts
@@ -1,3 +1,19 @@
+export interface ObjectUnsubscribedError extends Error {
+}
+
+export interface ObjectUnsubscribedErrorCtor {
+  new(): ObjectUnsubscribedError;
+}
+
+function ObjectUnsubscribedErrorImpl(this: any) {
+  Error.call(this);
+  this.message = 'object unsubscribed';
+  this.name = 'ObjectUnsubscribedError';
+  return this;
+}
+
+ObjectUnsubscribedErrorImpl.prototype = Object.create(Error.prototype);
+
 /**
  * An error thrown when an action is invalid because the object has been
  * unsubscribed.
@@ -7,12 +23,4 @@
  *
  * @class ObjectUnsubscribedError
  */
-export class ObjectUnsubscribedError extends Error {
-
-  public readonly name = 'ObjectUnsubscribedError';
-
-  constructor() {
-    super('object unsubscribed');
-    (Object as any).setPrototypeOf(this, ObjectUnsubscribedError.prototype);
-  }
-}
+export const ObjectUnsubscribedError: ObjectUnsubscribedErrorCtor = ObjectUnsubscribedErrorImpl as any;
\ No newline at end of file
diff --git a/src/internal/util/TimeoutError.ts b/src/internal/util/TimeoutError.ts
index e0a347c79b..a36162d9be 100644
--- a/src/internal/util/TimeoutError.ts
+++ b/src/internal/util/TimeoutError.ts
@@ -1,16 +1,24 @@
-/**
- * An error thrown when duetime elapses.
- *
- * @see {@link timeout}
- *
- * @class TimeoutError
- */
-export class TimeoutError extends Error {
-
-  public readonly name = 'TimeoutError';
-
-  constructor() {
-    super('Timeout has occurred');
-    (Object as any).setPrototypeOf(this, TimeoutError.prototype);
-  }
-}
+export interface TimeoutError extends Error {
+}
+
+export interface TimeoutErrorCtor {
+  new(): TimeoutError;
+}
+
+function TimeoutErrorImpl(this: any) {
+  Error.call(this);
+  this.message = 'Timeout has occurred';
+  this.name = 'TimeoutError';
+  return this;
+}
+
+TimeoutErrorImpl.prototype = Object.create(Error.prototype);
+
+/**
+ * An error thrown when duetime elapses.
+ *
+ * @see {@link timeout}
+ *
+ * @class TimeoutError
+ */
+export const TimeoutError: TimeoutErrorCtor = TimeoutErrorImpl as any;
diff --git a/src/internal/util/UnsubscriptionError.ts b/src/internal/util/UnsubscriptionError.ts
index 060096b719..293b9678a9 100644
--- a/src/internal/util/UnsubscriptionError.ts
+++ b/src/internal/util/UnsubscriptionError.ts
@@ -1,15 +1,25 @@
+export interface UnsubscriptionError extends Error {
+  readonly errors: any[];
+}
+
+export interface UnsubscriptionErrorCtor {
+  new(errors: any[]): UnsubscriptionError;
+}
+
+function UnsubscriptionErrorImpl(this: any, errors: any[]) {
+  Error.call(this);
+  this.message = errors ?
+  `${errors.length} errors occurred during unsubscription:
+${errors.map((err, i) => `${i + 1}) ${err.toString()}`).join('\n  ')}` : '';
+  this.name = 'UnsubscriptionError';
+  this.errors = errors;
+  return this;
+}
+
+UnsubscriptionErrorImpl.prototype = Object.create(Error.prototype);
+
 /**
  * An error thrown when one or more errors have occurred during the
  * `unsubscribe` of a {@link Subscription}.
  */
-export class UnsubscriptionError extends Error {
-
-  public readonly name = 'UnsubscriptionError';
-
-  constructor(public errors: any[]) {
-    super(errors ?
-      `${errors.length} errors occurred during unsubscription:
-  ${errors.map((err, i) => `${i + 1}) ${err.toString()}`).join('\n  ')}` : '');
-    (Object as any).setPrototypeOf(this, UnsubscriptionError.prototype);
-  }
-}
+export const UnsubscriptionError: UnsubscriptionErrorCtor = UnsubscriptionErrorImpl as any;
\ No newline at end of file