diff --git a/testdata/channel.go b/testdata/channel.go
index 63011d50..52d498fc 100644
--- a/testdata/channel.go
+++ b/testdata/channel.go
@@ -2,45 +2,17 @@ package main
 
 import (
 	"runtime"
+	"sync"
 	"time"
 )
 
-// waitGroup is a small type reimplementing some of the behavior of sync.WaitGroup
-type waitGroup uint
-
-func (wg *waitGroup) wait() {
-	n := 0
-	for *wg != 0 {
-		// pause and wait to be rescheduled
-		runtime.Gosched()
-
-		if n > 100 {
-			// if something is using the sleep queue, this may be necessary
-			time.Sleep(time.Millisecond)
-		}
-
-		n++
-	}
-}
-
-func (wg *waitGroup) add(n uint) {
-	*wg += waitGroup(n)
-}
-
-func (wg *waitGroup) done() {
-	if *wg == 0 {
-		panic("wait group underflow")
-	}
-	*wg--
-}
-
-var wg waitGroup
+var wg sync.WaitGroup
 
 func main() {
 	ch := make(chan int)
 	println("len, cap of channel:", len(ch), cap(ch), ch == nil)
 
-	wg.add(1)
+	wg.Add(1)
 	go sender(ch)
 
 	n, ok := <-ch
@@ -50,7 +22,7 @@ func main() {
 		println("received num:", n)
 	}
 
-	wg.wait()
+	wg.Wait()
 	n, ok = <-ch
 	println("recv from closed channel:", n, ok)
 
@@ -66,55 +38,55 @@ func main() {
 
 	// Test bigger values
 	ch2 := make(chan complex128)
-	wg.add(1)
+	wg.Add(1)
 	go sendComplex(ch2)
 	println("complex128:", <-ch2)
-	wg.wait()
+	wg.Wait()
 
 	// Test multi-sender.
 	ch = make(chan int)
-	wg.add(3)
+	wg.Add(3)
 	go fastsender(ch, 10)
 	go fastsender(ch, 23)
 	go fastsender(ch, 40)
 	slowreceiver(ch)
-	wg.wait()
+	wg.Wait()
 
 	// Test multi-receiver.
 	ch = make(chan int)
-	wg.add(3)
+	wg.Add(3)
 	go fastreceiver(ch)
 	go fastreceiver(ch)
 	go fastreceiver(ch)
 	slowsender(ch)
-	wg.wait()
+	wg.Wait()
 
 	// Test iterator style channel.
 	ch = make(chan int)
-	wg.add(1)
+	wg.Add(1)
 	go iterator(ch, 100)
 	sum := 0
 	for i := range ch {
 		sum += i
 	}
-	wg.wait()
+	wg.Wait()
 	println("sum(100):", sum)
 
 	// Test simple selects.
 	go selectDeadlock() // cannot use waitGroup here - never terminates
-	wg.add(1)
+	wg.Add(1)
 	go selectNoOp()
-	wg.wait()
+	wg.Wait()
 
 	// Test select with a single send operation (transformed into chan send).
 	ch = make(chan int)
-	wg.add(1)
+	wg.Add(1)
 	go fastreceiver(ch)
 	select {
 	case ch <- 5:
 	}
 	close(ch)
-	wg.wait()
+	wg.Wait()
 	println("did send one")
 
 	// Test select with a single recv operation (transformed into chan recv).
@@ -125,11 +97,11 @@ func main() {
 
 	// Test select recv with channel that has one entry.
 	ch = make(chan int)
-	wg.add(1)
+	wg.Add(1)
 	go func(ch chan int) {
 		runtime.Gosched()
 		ch <- 55
-		wg.done()
+		wg.Done()
 	}(ch)
 	select {
 	case make(chan int) <- 3:
@@ -141,7 +113,7 @@ func main() {
 	case n := <-make(chan int):
 		println("unreachable:", n)
 	}
-	wg.wait()
+	wg.Wait()
 
 	// Test select recv with closed channel.
 	close(ch)
@@ -156,7 +128,7 @@ func main() {
 
 	// Test select send.
 	ch = make(chan int)
-	wg.add(1)
+	wg.Add(1)
 	go fastreceiver(ch)
 	select {
 	case ch <- 235:
@@ -165,7 +137,7 @@ func main() {
 		println("unreachable:", n)
 	}
 	close(ch)
-	wg.wait()
+	wg.Wait()
 
 	// test non-concurrent buffered channels
 	ch = make(chan int, 2)
@@ -183,7 +155,7 @@ func main() {
 	println("closed buffered channel recieve:", <-ch)
 
 	// test using buffered channels as regular channels with special properties
-	wg.add(6)
+	wg.Add(6)
 	ch = make(chan int, 2)
 	go send(ch)
 	go send(ch)
@@ -191,7 +163,7 @@ func main() {
 	go send(ch)
 	go receive(ch)
 	go receive(ch)
-	wg.wait()
+	wg.Wait()
 	close(ch)
 	var count int
 	for range ch {
@@ -204,19 +176,19 @@ func main() {
 	sch1 := make(chan int)
 	sch2 := make(chan int)
 	sch3 := make(chan int)
-	wg.add(3)
+	wg.Add(3)
 	go func() {
-		defer wg.done()
+		defer wg.Done()
 		time.Sleep(time.Millisecond)
 		sch1 <- 1
 	}()
 	go func() {
-		defer wg.done()
+		defer wg.Done()
 		time.Sleep(time.Millisecond)
 		sch2 <- 2
 	}()
 	go func() {
-		defer wg.done()
+		defer wg.Done()
 		// merge sch2 and sch3 into ch
 		for i := 0; i < 2; i++ {
 			var v int
@@ -240,18 +212,18 @@ func main() {
 			sum += v
 		}
 	}
-	wg.wait()
+	wg.Wait()
 	println("blocking select sum:", sum)
 }
 
 func send(ch chan<- int) {
 	ch <- 1
-	wg.done()
+	wg.Done()
 }
 
 func receive(ch <-chan int) {
 	<-ch
-	wg.done()
+	wg.Done()
 }
 
 func sender(ch chan int) {
@@ -263,18 +235,18 @@ func sender(ch chan int) {
 		ch <- i
 	}
 	close(ch)
-	wg.done()
+	wg.Done()
 }
 
 func sendComplex(ch chan complex128) {
 	ch <- 7 + 10.5i
-	wg.done()
+	wg.Done()
 }
 
 func fastsender(ch chan int, n int) {
 	ch <- n
 	ch <- n + 1
-	wg.done()
+	wg.Done()
 }
 
 func slowreceiver(ch chan int) {
@@ -300,7 +272,7 @@ func fastreceiver(ch chan int) {
 		sum += n
 	}
 	println("sum:", sum)
-	wg.done()
+	wg.Done()
 }
 
 func iterator(ch chan int, top int) {
@@ -308,7 +280,7 @@ func iterator(ch chan int, top int) {
 		ch <- i
 	}
 	close(ch)
-	wg.done()
+	wg.Done()
 }
 
 func selectDeadlock() {
@@ -323,5 +295,5 @@ func selectNoOp() {
 	default:
 	}
 	println("after no-op")
-	wg.done()
+	wg.Done()
 }