diff --git a/lib.go b/lib.go
index 34ef38d..59c9b0f 100644
--- a/lib.go
+++ b/lib.go
@@ -3,6 +3,7 @@ package httpcli
 import (
 	"bytes"
 	"encoding/json"
+	"errors"
 	"io"
 	"net/http"
 	"strings"