diff --git a/spec/operators/take-spec.ts b/spec/operators/take-spec.ts
index 07c80dc096..e18fdfa443 100644
--- a/spec/operators/take-spec.ts
+++ b/spec/operators/take-spec.ts
@@ -4,8 +4,6 @@ import { range, ArgumentOutOfRangeError, of, Observable, Subject } from 'rxjs';
 import { TestScheduler } from 'rxjs/testing';
 import { observableMatcher } from '../helpers/observableMatcher';
 
-declare function asDiagram(arg: string): Function;
-
 /** @test {take} */
 describe('take operator', () => {
   let testScheduler: TestScheduler;
@@ -14,7 +12,28 @@ describe('take operator', () => {
     testScheduler = new TestScheduler(observableMatcher);
   });
 
-  asDiagram('take(2)')('should take two values of an observable with many values', () => {
+  it('should error when a non-number is passed to it, or when no argument is passed (Non-TS case)', () => {
+    expect(() => {
+      of(1, 2, 3).pipe(
+        (take as any)()
+      );
+    }).to.throw(TypeError, `'count' is not a number`);
+
+    expect(() => {
+      of(1, 2, 3).pipe(
+        (take as any)('banana')
+      );
+    }).to.throw(TypeError, `'count' is not a number`);
+
+    // Standard type coersion behavior in JS.
+    expect(() => {
+      of(1, 2, 3).pipe(
+        (take as any)('1')
+      );
+    }).not.to.throw();
+  });
+
+  it('should take two values of an observable with many values', () => {
     testScheduler.run(({ cold, expectObservable, expectSubscriptions }) => {
       const e1 = cold(' --a-----b----c---d--|');
       const e1subs = '  ^-------!------------';
diff --git a/spec/operators/takeLast-spec.ts b/spec/operators/takeLast-spec.ts
index 95a3927748..009aa92c3e 100644
--- a/spec/operators/takeLast-spec.ts
+++ b/spec/operators/takeLast-spec.ts
@@ -1,164 +1,216 @@
 import { expect } from 'chai';
-import { hot, cold, expectObservable, expectSubscriptions } from '../helpers/marble-testing';
 import { takeLast, mergeMap } from 'rxjs/operators';
 import { range, ArgumentOutOfRangeError, of } from 'rxjs';
-
-declare function asDiagram(arg: string): Function;
+import { TestScheduler } from 'rxjs/testing';
+import { assertDeepEquals } from '../helpers/test-helper';
 
 /** @test {takeLast} */
 describe('takeLast operator', () => {
-  asDiagram('takeLast(2)')('should take two values of an observable with many values', () => {
-    const e1 =  cold('--a-----b----c---d--|    ');
-    const e1subs =   '^                   !    ';
-    const expected = '--------------------(cd|)';
+  let rxTest: TestScheduler;
+
+  beforeEach(() => {
+    rxTest = new TestScheduler(assertDeepEquals);
+  });
+
+  it('should error for invalid arguments', () => {
+    expect(() => {
+      of(1, 2, 3).pipe((takeLast as any)());
+    }).to.throw(TypeError, `'count' is not a number`);
+
+    expect(() => {
+      of(1, 2, 3).pipe((takeLast as any)('banana'));
+    }).to.throw(TypeError, `'count' is not a number`);
+
+    expect(() => {
+      of(1, 2, 3).pipe((takeLast as any)('3'));
+    }).not.to.throw();
+  });
+
+  it('should take two values of an observable with many values', () => {
+    rxTest.run(({ cold, expectObservable, expectSubscriptions }) => {
+      const e1 = cold('--a-----b----c---d--|    ');
+      const e1subs = ' ^-------------------!    ';
+      const expected = '--------------------(cd|)';
 
-    expectObservable(e1.pipe(takeLast(2))).toBe(expected);
-    expectSubscriptions(e1.subscriptions).toBe(e1subs);
+      expectObservable(e1.pipe(takeLast(2))).toBe(expected);
+      expectSubscriptions(e1.subscriptions).toBe(e1subs);
+    });
   });
 
   it('should take last three values', () => {
-    const e1 =  cold('--a-----b----c---d--|    ');
-    const e1subs =   '^                   !    ';
-    const expected = '--------------------(bcd|)';
+    rxTest.run(({ cold, expectObservable, expectSubscriptions }) => {
+      const e1 = cold(' --a-----b----c---d--|    ');
+      const e1subs = '  ^-------------------!    ';
+      const expected = '--------------------(bcd|)';
 
-    expectObservable(e1.pipe(takeLast(3))).toBe(expected);
-    expectSubscriptions(e1.subscriptions).toBe(e1subs);
+      expectObservable(e1.pipe(takeLast(3))).toBe(expected);
+      expectSubscriptions(e1.subscriptions).toBe(e1subs);
+    });
   });
 
   it('should take all element when try to take larger then source', () => {
-    const e1 =  cold('--a-----b----c---d--|    ');
-    const e1subs =   '^                   !    ';
-    const expected = '--------------------(abcd|)';
+    rxTest.run(({ cold, expectObservable, expectSubscriptions }) => {
+      const e1 = cold(' --a-----b----c---d--|    ');
+      const e1subs = '  ^-------------------!    ';
+      const expected = '--------------------(abcd|)';
 
-    expectObservable(e1.pipe(takeLast(5))).toBe(expected);
-    expectSubscriptions(e1.subscriptions).toBe(e1subs);
+      expectObservable(e1.pipe(takeLast(5))).toBe(expected);
+      expectSubscriptions(e1.subscriptions).toBe(e1subs);
+    });
   });
 
   it('should take all element when try to take exact', () => {
-    const e1 =  cold('--a-----b----c---d--|    ');
-    const e1subs =   '^                   !    ';
-    const expected = '--------------------(abcd|)';
+    rxTest.run(({ cold, expectObservable, expectSubscriptions }) => {
+      const e1 = cold(' --a-----b----c---d--|    ');
+      const e1subs = '  ^-------------------!    ';
+      const expected = '--------------------(abcd|)';
 
-    expectObservable(e1.pipe(takeLast(4))).toBe(expected);
-    expectSubscriptions(e1.subscriptions).toBe(e1subs);
+      expectObservable(e1.pipe(takeLast(4))).toBe(expected);
+      expectSubscriptions(e1.subscriptions).toBe(e1subs);
+    });
   });
 
   it('should not take any values', () => {
-    const e1 =  cold('--a-----b----c---d--|');
-    const expected = '|';
+    rxTest.run(({ cold, expectObservable }) => {
+      const e1 = cold(' --a-----b----c---d--|');
+      const expected = '|';
 
-    expectObservable(e1.pipe(takeLast(0))).toBe(expected);
+      expectObservable(e1.pipe(takeLast(0))).toBe(expected);
+    });
   });
 
   it('should work with empty', () => {
-    const e1 =  cold('|');
-    const e1subs =   '(^!)';
-    const expected = '|';
+    rxTest.run(({ cold, expectObservable, expectSubscriptions }) => {
+      const e1 = cold(' |');
+      const e1subs = '  (^!)';
+      const expected = '|';
 
-    expectObservable(e1.pipe(takeLast(42))).toBe(expected);
-    expectSubscriptions(e1.subscriptions).toBe(e1subs);
+      expectObservable(e1.pipe(takeLast(42))).toBe(expected);
+      expectSubscriptions(e1.subscriptions).toBe(e1subs);
+    });
   });
 
   it('should go on forever on never', () => {
-    const e1 =  cold('-');
-    const e1subs =   '^';
-    const expected = '-';
+    rxTest.run(({ cold, expectObservable, expectSubscriptions }) => {
+      const e1 = cold(' -');
+      const e1subs = '  ^';
+      const expected = '-';
 
-    expectObservable(e1.pipe(takeLast(42))).toBe(expected);
-    expectSubscriptions(e1.subscriptions).toBe(e1subs);
+      expectObservable(e1.pipe(takeLast(42))).toBe(expected);
+      expectSubscriptions(e1.subscriptions).toBe(e1subs);
+    });
   });
 
   it('should be empty on takeLast(0)', () => {
-    const e1 = hot('--a--^--b----c---d--|');
-    const e1subs: string[] = []; // Don't subscribe at all
-    const expected =    '|';
+    rxTest.run(({ hot, expectObservable, expectSubscriptions }) => {
+      const e1 = hot('--a--^--b----c---d--|');
+      const expected = '   |';
+      const e1subs: string[] = []; // Don't subscribe at all
 
-    expectObservable(e1.pipe(takeLast(0))).toBe(expected);
-    expectSubscriptions(e1.subscriptions).toBe(e1subs);
+      expectObservable(e1.pipe(takeLast(0))).toBe(expected);
+      expectSubscriptions(e1.subscriptions).toBe(e1subs);
+    });
   });
 
   it('should take one value from an observable with one value', () => {
-    const e1 =   hot('---(a|)');
-    const e1subs =   '^  !   ';
-    const expected = '---(a|)';
+    rxTest.run(({ hot, expectObservable, expectSubscriptions }) => {
+      const e1 = hot('  ---(a|)');
+      const e1subs = '  ^--!   ';
+      const expected = '---(a|)';
 
-    expectObservable(e1.pipe(takeLast(1))).toBe(expected);
-    expectSubscriptions(e1.subscriptions).toBe(e1subs);
+      expectObservable(e1.pipe(takeLast(1))).toBe(expected);
+      expectSubscriptions(e1.subscriptions).toBe(e1subs);
+    });
   });
 
   it('should take one value from an observable with many values', () => {
-    const e1 = hot('--a--^--b----c---d--|   ');
-    const e1subs =      '^              !   ';
-    const expected =    '---------------(d|)';
+    rxTest.run(({ hot, expectObservable, expectSubscriptions }) => {
+      const e1 = hot('--a--^--b----c---d--|   ');
+      const e1subs = '     ^--------------!   ';
+      const expected = '   ---------------(d|)';
 
-    expectObservable(e1.pipe(takeLast(1))).toBe(expected);
-    expectSubscriptions(e1.subscriptions).toBe(e1subs);
+      expectObservable(e1.pipe(takeLast(1))).toBe(expected);
+      expectSubscriptions(e1.subscriptions).toBe(e1subs);
+    });
   });
 
   it('should error on empty', () => {
-    const e1 = hot('--a--^----|');
-    const e1subs =      '^    !';
-    const expected =    '-----|';
+    rxTest.run(({ hot, expectObservable, expectSubscriptions }) => {
+      const e1 = hot('--a--^----|');
+      const e1subs = '     ^----!';
+      const expected = '   -----|';
 
-    expectObservable(e1.pipe(takeLast(42))).toBe(expected);
-    expectSubscriptions(e1.subscriptions).toBe(e1subs);
+      expectObservable(e1.pipe(takeLast(42))).toBe(expected);
+      expectSubscriptions(e1.subscriptions).toBe(e1subs);
+    });
   });
 
   it('should propagate error from the source observable', () => {
-    const e1 = hot('---^---#', undefined, 'too bad');
-    const e1subs =    '^   !';
-    const expected =  '----#';
+    rxTest.run(({ hot, expectObservable, expectSubscriptions }) => {
+      const e1 = hot('---^---#', undefined, 'too bad');
+      const e1subs = '   ^---!';
+      const expected = ' ----#';
 
-    expectObservable(e1.pipe(takeLast(42))).toBe(expected, null, 'too bad');
-    expectSubscriptions(e1.subscriptions).toBe(e1subs);
+      expectObservable(e1.pipe(takeLast(42))).toBe(expected, null, 'too bad');
+      expectSubscriptions(e1.subscriptions).toBe(e1subs);
+    });
   });
 
   it('should propagate error from an observable with values', () => {
-    const e1 = hot('---^--a--b--#');
-    const e1subs =    '^        !';
-    const expected =  '---------#';
+    rxTest.run(({ hot, expectObservable, expectSubscriptions }) => {
+      const e1 = hot('---^--a--b--#');
+      const e1subs = '   ^--------!';
+      const expected = ' ---------#';
 
-    expectObservable(e1.pipe(takeLast(42))).toBe(expected);
-    expectSubscriptions(e1.subscriptions).toBe(e1subs);
+      expectObservable(e1.pipe(takeLast(42))).toBe(expected);
+      expectSubscriptions(e1.subscriptions).toBe(e1subs);
+    });
   });
 
   it('should allow unsubscribing explicitly and early', () => {
-    const e1 = hot('---^--a--b-----c--d--e--|');
-    const unsub =     '         !            ';
-    const e1subs =    '^        !            ';
-    const expected =  '----------            ';
+    rxTest.run(({ hot, expectObservable, expectSubscriptions }) => {
+      const e1 = hot('---^--a--b-----c--d--e--|');
+      const unsub = '    ---------!            ';
+      const e1subs = '   ^--------!            ';
+      const expected = ' ----------------------';
 
-    expectObservable(e1.pipe(takeLast(42)), unsub).toBe(expected);
-    expectSubscriptions(e1.subscriptions).toBe(e1subs);
+      expectObservable(e1.pipe(takeLast(42)), unsub).toBe(expected);
+      expectSubscriptions(e1.subscriptions).toBe(e1subs);
+    });
   });
 
   it('should work with throw', () => {
-    const e1 =  cold('#');
-    const e1subs =   '(^!)';
-    const expected = '#';
+    rxTest.run(({ cold, expectObservable, expectSubscriptions }) => {
+      const e1 = cold(' #');
+      const e1subs = '  (^!)';
+      const expected = '#';
 
-    expectObservable(e1.pipe(takeLast(42))).toBe(expected);
-    expectSubscriptions(e1.subscriptions).toBe(e1subs);
+      expectObservable(e1.pipe(takeLast(42))).toBe(expected);
+      expectSubscriptions(e1.subscriptions).toBe(e1subs);
+    });
   });
 
   it('should throw if total is less than zero', () => {
-    expect(() => { range(0, 10).pipe(takeLast(-1)); })
-      .to.throw(ArgumentOutOfRangeError);
+    expect(() => {
+      range(0, 10).pipe(takeLast(-1));
+    }).to.throw(ArgumentOutOfRangeError);
   });
 
   it('should not break unsubscription chain when unsubscribed explicitly', () => {
-    const e1 = hot('---^--a--b-----c--d--e--|');
-    const unsub =     '         !            ';
-    const e1subs =    '^        !            ';
-    const expected =  '----------            ';
-
-    const result = e1.pipe(
-      mergeMap((x: string) => of(x)),
-      takeLast(42),
-      mergeMap((x: string) => of(x))
-    );
-
-    expectObservable(result, unsub).toBe(expected);
-    expectSubscriptions(e1.subscriptions).toBe(e1subs);
+    rxTest.run(({ hot, expectObservable, expectSubscriptions }) => {
+      const e1 = hot('---^--a--b-----c--d--e--|');
+      const unsub = '    ---------!            ';
+      const e1subs = '   ^--------!            ';
+      const expected = ' ----------------------';
+
+      const result = e1.pipe(
+        mergeMap((x: string) => of(x)),
+        takeLast(42),
+        mergeMap((x: string) => of(x))
+      );
+
+      expectObservable(result, unsub).toBe(expected);
+      expectSubscriptions(e1.subscriptions).toBe(e1subs);
+    });
   });
 });
diff --git a/src/internal/operators/take.ts b/src/internal/operators/take.ts
index 7058c13f3d..c525b020fd 100644
--- a/src/internal/operators/take.ts
+++ b/src/internal/operators/take.ts
@@ -1,9 +1,9 @@
 import { Operator } from '../Operator';
 import { Subscriber } from '../Subscriber';
 import { ArgumentOutOfRangeError } from '../util/ArgumentOutOfRangeError';
-import { EMPTY } from '../observable/empty';
 import { Observable } from '../Observable';
 import { MonoTypeOperatorFunction, TeardownLogic } from '../types';
+import { EMPTY } from '../observable/empty';
 
 /**
  * Emits only the first `count` values emitted by the source Observable.
@@ -43,50 +43,42 @@ import { MonoTypeOperatorFunction, TeardownLogic } from '../types';
  *
  * @throws {ArgumentOutOfRangeError} When using `take(i)`, it delivers an
  * ArgumentOutOrRangeError to the Observer's `error` callback if `i < 0`.
- *
- * @param {number} count The maximum number of `next` values to emit.
- * @return {Observable<T>} An Observable that emits only the first `count`
+ * @throws {TypeError} when no numeric argument is passed.
+ * @param count The maximum number of `next` values to emit.
+ * @return An Observable that emits only the first `count`
  * values emitted by the source Observable, or all of the values from the source
  * if the source emits fewer than `count` values.
- * @name take
  */
 export function take<T>(count: number): MonoTypeOperatorFunction<T> {
-  return (source: Observable<T>) => {
-    if (count === 0) {
-      return EMPTY;
-    } else {
-      return source.lift(new TakeOperator(count));
-    }
-  };
+  if (isNaN(count)) {
+    throw new TypeError(`'count' is not a number`);
+  }
+  if (count < 0) {
+    throw new ArgumentOutOfRangeError;
+  }
+
+  return (source: Observable<T>) => (count === 0) ? EMPTY : source.lift(new TakeOperator(count));
 }
 
 class TakeOperator<T> implements Operator<T, T> {
-  constructor(private total: number) {
-    if (this.total < 0) {
-      throw new ArgumentOutOfRangeError;
-    }
+  constructor(private count: number) {
   }
 
   call(subscriber: Subscriber<T>, source: any): TeardownLogic {
-    return source.subscribe(new TakeSubscriber(subscriber, this.total));
+    return source.subscribe(new TakeSubscriber(subscriber, this.count));
   }
 }
 
-/**
- * We need this JSDoc comment for affecting ESDoc.
- * @ignore
- * @extends {Ignored}
- */
 class TakeSubscriber<T> extends Subscriber<T> {
-  private count: number = 0;
+  private _valueCount: number = 0;
 
-  constructor(destination: Subscriber<T>, private total: number) {
+  constructor(destination: Subscriber<T>, private count: number) {
     super(destination);
   }
 
   protected _next(value: T): void {
-    const total = this.total;
-    const count = ++this.count;
+    const total = this.count;
+    const count = ++this._valueCount;
     if (count <= total) {
       this.destination.next(value);
       if (count === total) {
diff --git a/src/internal/operators/takeLast.ts b/src/internal/operators/takeLast.ts
index aff9d4204c..36c77d0bb7 100644
--- a/src/internal/operators/takeLast.ts
+++ b/src/internal/operators/takeLast.ts
@@ -39,14 +39,21 @@ import { MonoTypeOperatorFunction, TeardownLogic } from '../types';
  *
  * @throws {ArgumentOutOfRangeError} When using `takeLast(i)`, it delivers an
  * ArgumentOutOrRangeError to the Observer's `error` callback if `i < 0`.
+ * @throws {TypeError} If the count is not provided or is not a number.
  *
- * @param {number} count The maximum number of values to emit from the end of
+ * @param count The maximum number of values to emit from the end of
  * the sequence of values emitted by the source Observable.
- * @return {Observable<T>} An Observable that emits at most the last count
+ * @return An Observable that emits at most the last count
  * values emitted by the source Observable.
- * @name takeLast
  */
 export function takeLast<T>(count: number): MonoTypeOperatorFunction<T> {
+  if (isNaN(count)) {
+    throw new TypeError(`'count' is not a number`);
+  }
+  if (count < 0) {
+    throw new ArgumentOutOfRangeError;
+  }
+
   return function takeLastOperatorFunction(source: Observable<T>): Observable<T> {
     if (count === 0) {
       return EMPTY;
@@ -58,9 +65,6 @@ export function takeLast<T>(count: number): MonoTypeOperatorFunction<T> {
 
 class TakeLastOperator<T> implements Operator<T, T> {
   constructor(private total: number) {
-    if (this.total < 0) {
-      throw new ArgumentOutOfRangeError;
-    }
   }
 
   call(subscriber: Subscriber<T>, source: any): TeardownLogic {
@@ -68,11 +72,6 @@ class TakeLastOperator<T> implements Operator<T, T> {
   }
 }
 
-/**
- * We need this JSDoc comment for affecting ESDoc.
- * @ignore
- * @extends {Ignored}
- */
 class TakeLastSubscriber<T> extends Subscriber<T> {
   private ring: Array<T> = new Array();
   private count: number = 0;