diff --git a/spec/operators/throttleTime-spec.ts b/spec/operators/throttleTime-spec.ts
index 4e65054ae8..899635f15f 100644
--- a/spec/operators/throttleTime-spec.ts
+++ b/spec/operators/throttleTime-spec.ts
@@ -141,11 +141,11 @@ describe('throttleTime operator', () => {
   });
 
   describe('throttleTime(fn, { leading: true, trailing: true })', () => {
-    asDiagram('throttleTime(fn, { leading: true, trailing: true })')('should immediately emit the first and last values in each time window', () =>  {
-      const e1 =   hot('-a-xy-----b--x--cxxx--|');
-      const e1subs =   '^                     !';
+    asDiagram('throttleTime(fn, { leading: true, trailing: true })')('should emit only one value in given time window', () =>  {
+      const e1 =   hot('-a-xy-----b--x--cxxx---|');
+      const e1subs =   '^                      !';
       const t =  time( '----|                  ');
-      const expected = '-a---y----b---x-c---x-|';
+      const expected = '-a---y----b---x---x---x|';
 
       const result = e1.pipe(throttleTime(t, rxTestScheduler, { leading: true, trailing: true }));
 
@@ -153,6 +153,15 @@ describe('throttleTime operator', () => {
       expectSubscriptions(e1.subscriptions).toBe(e1subs);
     });
 
+    it('should handle a busy producer emitting a regular repeating sequence', () => {
+      const e1 =   hot('abcdeabcdeabcdeabcdea|');
+      const subs =     '^                    !';
+      const expected = 'a----a----a----a----a|';
+
+      expectObservable(e1.pipe(throttleTime(50, rxTestScheduler, { leading: true, trailing: true }))).toBe(expected);
+      expectSubscriptions(e1.subscriptions).toBe(subs);
+    });
+
     it('should emit the value if only a single one is given', () => {
       const e1 =   hot('-a--------------------|');
       const t =   time('----|                  ');
@@ -166,10 +175,10 @@ describe('throttleTime operator', () => {
 
   describe('throttleTime(fn, { leading: false, trailing: true })', () => {
     asDiagram('throttleTime(fn, { leading: false, trailing: true })')('should immediately emit the last value in each time window', () =>  {
-      const e1 =   hot('-a-xy-----b--x--cxxx--|');
-      const e1subs =   '^                     !';
+      const e1 =   hot('-a-xy-----b--x--cxxx---|');
+      const e1subs =   '^                      !';
       const t =  time( '----|                  ');
-      const expected = '-----y--------x-----x-|';
+      const expected = '-----y--------x---x---x|';
 
       const result = e1.pipe(throttleTime(t, rxTestScheduler, { leading: false, trailing: true }));
 
@@ -178,10 +187,10 @@ describe('throttleTime operator', () => {
     });
 
     it('should emit the last throttled value when complete', () => {
-      const e1 =   hot('-a-xy-----b--x--cxx|');
-      const e1subs =   '^                  !';
-      const t =   time('----|               ');
-      const expected = '-----y--------x----(x|)';
+      const e1 =   hot('-a-xy-----b--x-cxx|');
+      const e1subs =   '^                 !';
+      const t =   time('----|             ');
+      const expected = '-----y--------x---(x|)';
 
       const result = e1.pipe(throttleTime(t, rxTestScheduler, { leading: false, trailing: true }));
 
diff --git a/src/internal/operators/throttleTime.ts b/src/internal/operators/throttleTime.ts
index baed7785c2..21c9c9e675 100644
--- a/src/internal/operators/throttleTime.ts
+++ b/src/internal/operators/throttleTime.ts
@@ -153,13 +153,16 @@ class ThrottleTimeSubscriber<T> extends Subscriber<T> {
     const throttled = this.throttled;
     if (throttled) {
       if (this.trailing && this._hasTrailingValue) {
+        this.add(this.throttled = this.scheduler.schedule<DispatchArg<T>>(dispatchNext, this.duration, { subscriber: this }));
         this.destination.next(this._trailingValue);
         this._trailingValue = null;
         this._hasTrailingValue = false;
       }
       throttled.unsubscribe();
       this.remove(throttled);
-      this.throttled = null;
+      if (throttled === this.throttled) {
+        this.throttled = null;
+      }
     }
   }
 }