diff --git a/src/cmd/go/internal/par/work.go b/src/cmd/go/internal/par/work.go
index 6543f1a35c..a568c86f60 100644
--- a/src/cmd/go/internal/par/work.go
+++ b/src/cmd/go/internal/par/work.go
@@ -55,7 +55,6 @@ func (w *Work) Do(n int, f func(item interface{})) {
 	if n < 1 {
 		panic("par.Work.Do: n < 1")
 	}
-	n = 1
 	if w.running >= 1 {
 		panic("par.Work.Do: already called Do")
 	}
diff --git a/src/cmd/go/internal/par/work_test.go b/src/cmd/go/internal/par/work_test.go
index 71c0395d3b..53a715ea81 100644
--- a/src/cmd/go/internal/par/work_test.go
+++ b/src/cmd/go/internal/par/work_test.go
@@ -7,6 +7,7 @@ package par
 import (
 	"sync/atomic"
 	"testing"
+	"time"
 )
 
 func TestWork(t *testing.T) {
@@ -30,6 +31,30 @@ func TestWork(t *testing.T) {
 	}
 }
 
+func TestWorkParallel(t *testing.T) {
+	var w Work
+
+	for tries := 0; tries < 10; tries++ {
+		const N = 100
+		for i := 0; i < N; i++ {
+			w.Add(i)
+		}
+		start := time.Now()
+		var n int32
+		w.Do(N, func(x interface{}) {
+			time.Sleep(1 * time.Millisecond)
+			atomic.AddInt32(&n, +1)
+		})
+		if n != N {
+			t.Fatalf("par.Work.Do did not do all the work")
+		}
+		if time.Since(start) < N/2*time.Millisecond {
+			return
+		}
+	}
+	t.Fatalf("par.Work.Do does not seem to be parallel")
+}
+
 func TestCache(t *testing.T) {
 	var cache Cache