diff --git a/dl.go b/dl.go
index 4a485e7..0d652bb 100644
--- a/dl.go
+++ b/dl.go
@@ -6,7 +6,7 @@ import (
 	"net/http"
 )
 
-const dlURL = "https://golang.org/dl/?mode=json"
+var dlURL = "https://golang.org/dl/?mode=json"
 
 // Version is a Go version
 type Version struct {
diff --git a/dl_test.go b/dl_test.go
index bcab308..9421179 100644
--- a/dl_test.go
+++ b/dl_test.go
@@ -14,7 +14,7 @@ func TestVersions(t *testing.T) {
 	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		_, _ = w.Write(dlResp)
 	}))
-	http.DefaultClient = server.Client()
+	dlURL = server.URL
 
 	versions, err := Versions(context.Background())
 	if err != nil {