diff --git a/tools/testtool/freeport.go b/tools/testtool/freeport.go
index 197b3bf..437e0fd 100644
--- a/tools/testtool/freeport.go
+++ b/tools/testtool/freeport.go
@@ -3,7 +3,6 @@ package testtool
 import (
 	"fmt"
 	"net"
-	"os"
 	"strconv"
 	"time"
 )
@@ -26,10 +25,14 @@ func GetFreePort() (string, error) {
 	return strconv.Itoa(p), nil
 }
 
+type logger interface {
+	Logf(format string, args ...interface{})
+}
+
 // WaitForPort tries to connect to given local port with constant backoff.
 //
 // Returns error if port is not ready after timeout.
-func WaitForPort(timeout time.Duration, port string) error {
+func WaitForPort(l logger, timeout time.Duration, port string) error {
 	stopTimer := time.NewTimer(timeout)
 	defer stopTimer.Stop()
 
@@ -42,7 +45,7 @@ func WaitForPort(timeout time.Duration, port string) error {
 			return fmt.Errorf("no server started listening on port %s after timeout %d", port, timeout)
 		case <-t.C:
 			if err := portIsReady(port); err != nil {
-				_, _ = fmt.Fprintf(os.Stderr, "waiting for port: %s\n", err)
+				l.Logf("waiting for port: %s\n", err)
 				break
 			}
 			return nil
diff --git a/tools/testtool/freeport_test.go b/tools/testtool/freeport_test.go
index f9cbbbb..486fb44 100644
--- a/tools/testtool/freeport_test.go
+++ b/tools/testtool/freeport_test.go
@@ -26,12 +26,12 @@ func TestWaitForPort(t *testing.T) {
 	_, port, err := net.SplitHostPort(u.Host)
 	require.Nil(t, err)
 
-	require.NoError(t, WaitForPort(time.Second, port))
+	require.NoError(t, WaitForPort(t, time.Second, port))
 }
 
 func TestWaitForPort_timeout(t *testing.T) {
 	p, err := GetFreePort()
 	require.NoError(t, err)
 
-	require.Error(t, WaitForPort(time.Second, p))
+	require.Error(t, WaitForPort(t, time.Second, p))
 }