diff --git a/src_core/com/tenwa/doc/cache/DocListCache.java b/src_core/com/tenwa/doc/cache/DocListCache.java
index 1bc04e909..3d39d5a8e 100644
--- a/src_core/com/tenwa/doc/cache/DocListCache.java
+++ b/src_core/com/tenwa/doc/cache/DocListCache.java
@@ -18,7 +18,7 @@ public class DocListCache {
 		sb.append("{");
 		for(int i=0;i<list.size();i++){
 			BizObject bo=list.get(i);
-			sb.append(i+":{");
+			sb.append("\"" +i+"\""+":{");
 			String type=bo.getAttribute("CONTENT_TYPE").getString();
 			if(type.indexOf("image")>=0){
 				sb.append("\"image\":\""+true+"\",");