diff --git a/mall-admin/src/main/java/com/suisung/mall/admin/oss/service/impl/OssServiceImpl.java b/mall-admin/src/main/java/com/suisung/mall/admin/oss/service/impl/OssServiceImpl.java
index a15b4e0b..a7fa5262 100644
--- a/mall-admin/src/main/java/com/suisung/mall/admin/oss/service/impl/OssServiceImpl.java
+++ b/mall-admin/src/main/java/com/suisung/mall/admin/oss/service/impl/OssServiceImpl.java
@@ -105,7 +105,8 @@ public class OssServiceImpl implements OssService {
         // 根据用户获取目录名
         String dir = getUserDirName(user) + DateUtil.format(new Date(), "yyyyMMdd");
         // 创建唯一文件名称
-        String suffix = fileName.substring(fileName.lastIndexOf("."));
+        assert fileName != null;
+        String suffix = fileName.substring(fileName.lastIndexOf(".")).toLowerCase();
         String uploadName = IdUtil.simpleUUID() + suffix;
         String uploadPath = FILEPATH + "/" + dir + "/" + uploadName;