diff --git a/src/main/java/com/rymcu/forest/util/FileUtils.java b/src/main/java/com/rymcu/forest/util/FileUtils.java
index 696c30b..fda6463 100644
--- a/src/main/java/com/rymcu/forest/util/FileUtils.java
+++ b/src/main/java/com/rymcu/forest/util/FileUtils.java
@@ -24,7 +24,7 @@ public class FileUtils {
      * @return
      */
     public static String getExtend(String filename) {
-        return getExtend(filename, "");
+        return getExtend(filename, ".png");
     }
 
     /**