diff --git a/ch9/memotest/memotest.go b/ch9/memotest/memotest.go
index aab1acf..0c491c7 100644
--- a/ch9/memotest/memotest.go
+++ b/ch9/memotest/memotest.go
@@ -68,6 +68,7 @@ func Sequential(t *testing.T, m M) {
 		value, err := m.Get(url)
 		if err != nil {
 			log.Print(err)
+			continue
 		}
 		fmt.Printf("%s, %s, %d bytes\n",
 			url, time.Since(start), len(value.([]byte)))
@@ -87,14 +88,15 @@ func Concurrent(t *testing.T, m M) {
 	for url := range incomingURLs() {
 		n.Add(1)
 		go func(url string) {
+			defer n.Done()
 			start := time.Now()
 			value, err := m.Get(url)
 			if err != nil {
 				log.Print(err)
+				return
 			}
 			fmt.Printf("%s, %s, %d bytes\n",
 				url, time.Since(start), len(value.([]byte)))
-			n.Done()
 		}(url)
 	}
 	n.Wait()