diff --git a/core/src/main/java/com/wechat/pay/java/core/http/okhttp/OkHttpClientAdapter.java b/core/src/main/java/com/wechat/pay/java/core/http/okhttp/OkHttpClientAdapter.java
index a47cec00..78669ffb 100644
--- a/core/src/main/java/com/wechat/pay/java/core/http/okhttp/OkHttpClientAdapter.java
+++ b/core/src/main/java/com/wechat/pay/java/core/http/okhttp/OkHttpClientAdapter.java
@@ -68,7 +68,7 @@ private RequestBody buildOkHttpRequestBody(
       com.wechat.pay.java.core.http.RequestBody wechatPayRequestBody) {
     if (wechatPayRequestBody == null) {
       // create an empty request body
-      return RequestBody.create("", null);
+      return createOkHttpEmptyRequestBody();
     }
     if (wechatPayRequestBody instanceof JsonRequestBody) {
       return createOkHttpRequestBody(wechatPayRequestBody);
@@ -95,6 +95,10 @@ private okhttp3.RequestBody createRequestBody(byte[] content, okhttp3.MediaType
     return okhttp3.RequestBody.create(mediaType, content);
   }
 
+  private RequestBody createOkHttpEmptyRequestBody() {
+    return createRequestBody("", null);
+  }
+
   private RequestBody createOkHttpRequestBody(
       com.wechat.pay.java.core.http.RequestBody wechatPayRequestBody) {
     return createRequestBody(