diff --git a/go/internal/io/fio/client.go b/go/internal/io/fio/client.go
index 4ff3ae2..db40d54 100644
--- a/go/internal/io/fio/client.go
+++ b/go/internal/io/fio/client.go
@@ -4,6 +4,7 @@ package fio
 
 import (
 	"context"
+	"net/http"
 	"time"
 )
 
@@ -29,7 +30,11 @@ type Client interface {
 }
 
 // New returns an apiClient when token is non-empty, otherwise a transparentClient.
+// hc may be nil, in which case http.DefaultClient is used.
 func New(token, accountNum string, hc httpDoer) Client {
+	if hc == nil {
+		hc = http.DefaultClient
+	}
 	if token != "" {
 		return &apiClient{token: token, hc: hc}
 	}