diff --git a/connect_ext_test.go b/connect_ext_test.go
index f289f92a..e6b5a6eb 100644
--- a/connect_ext_test.go
+++ b/connect_ext_test.go
@@ -476,7 +476,7 @@ func TestConcurrentStreams(t *testing.T) {
 	server := memhttptest.NewServer(t, mux)
 	var done, start sync.WaitGroup
 	start.Add(1)
-	for i := 0; i < runtime.GOMAXPROCS(0)*2; i++ {
+	for i := 0; i < runtime.GOMAXPROCS(0)*8; i++ {
 		done.Add(1)
 		go func() {
 			defer done.Done()
@@ -511,8 +511,6 @@ func TestConcurrentStreams(t *testing.T) {
 	}
 	start.Done()
 	done.Wait()
-	t.Error("NUMCPU", runtime.NumCPU())
-	t.Error("GOMAXPROCS", runtime.GOMAXPROCS(0))
 }
 
 func TestHeaderBasic(t *testing.T) {
diff --git a/internal/memhttp/memhttp_test.go b/internal/memhttp/memhttp_test.go
index a12532c9..9218f7ed 100644
--- a/internal/memhttp/memhttp_test.go
+++ b/internal/memhttp/memhttp_test.go
@@ -31,7 +31,7 @@ import (
 
 func TestServerTransport(t *testing.T) {
 	t.Parallel()
-	concurrency := runtime.GOMAXPROCS(0) * 2
+	concurrency := runtime.GOMAXPROCS(0) * 8
 	const greeting = "Hello, world!"
 
 	handler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {