diff --git a/pkg/cover/instrument.go b/pkg/cover/instrument.go
index 63a007d..2a8c3e2 100644
--- a/pkg/cover/instrument.go
+++ b/pkg/cover/instrument.go
@@ -208,7 +208,11 @@ func registerSelf(address string) ([]byte, error) {
 		log.Printf("[goc][WARN]error occurred:%v, try again", err)
 		resp, err = http.DefaultClient.Do(req)
 	}
-	defer resp.Body.Close()
+	defer func() {
+		if resp != nil {
+			resp.Body.Close()
+		}
+	}()
 
 	if err != nil {
 		return nil, fmt.Errorf("failed to register into coverage center, err:%v", err)