diff --git a/lib/repo.vala b/lib/repo.vala
index 00c6c24..1b329c0 100644
--- a/lib/repo.vala
+++ b/lib/repo.vala
@@ -34,7 +34,7 @@ public class Repo : Object {
     // data format version
     public int version { get; set; }
 
-    public int    last_modify { get; set; }
+    public int64  last_modify { get; set; }
     public int64  size { get; set; }
     public int64  file_count { get; set; }
     public string last_modifier { get; set; }
@@ -46,7 +46,7 @@ public class Repo : Object {
     public string repo_id { get; set; }
     public string repo_name { get; set; }
     public string repo_desc { get; set; }
-    public int last_modified { get; set; }
+    public int64 last_modified { get; set; }
 
     // Section 2: Encryption related
     // Members in this section should be set for every Repo object