diff --git a/exercises/basics/06-concurrency/01-goroutines/src_test.go b/exercises/basics/06-concurrency/01-goroutines/src_test.go
index d43bc16..35c531f 100644
--- a/exercises/basics/06-concurrency/01-goroutines/src_test.go
+++ b/exercises/basics/06-concurrency/01-goroutines/src_test.go
@@ -14,7 +14,7 @@ func TestExecute(t *testing.T) {
 	func() {
 		buffers := make(chan *bytes.Buffer)
 		go func(done chan *bytes.Buffer) {
-			buffers <- Execute(10)
+			done <- Execute(10)
 		}(buffers)
 
 		select {
diff --git a/solutions/basics/06-concurrency/01-goroutines/src.go b/solutions/basics/06-concurrency/01-goroutines/src.go
index 0c6a233..1a540d6 100644
--- a/solutions/basics/06-concurrency/01-goroutines/src.go
+++ b/solutions/basics/06-concurrency/01-goroutines/src.go
@@ -10,6 +10,9 @@ import (
 // Maybe if we ran all the long processes concurrently, it would be much faster.
 // Let's do that!
 // Beware, all the processes must end before that Execute returns.
+
+var m sync.Mutex
+
 func Execute(nbProcess int) *bytes.Buffer {
 	buf := new(bytes.Buffer)
 	wg := &sync.WaitGroup{}
@@ -26,5 +29,7 @@ func Execute(nbProcess int) *bytes.Buffer {
 
 func someReallyLongProcess(buf *bytes.Buffer) {
 	time.Sleep(1 * time.Second)
+	m.Lock()
+	defer m.Unlock()
 	buf.WriteString("Done\n")
 }