diff --git a/packages/hydrojudge/package.json b/packages/hydrojudge/package.json
index 85f283aae..a2a391d80 100644
--- a/packages/hydrojudge/package.json
+++ b/packages/hydrojudge/package.json
@@ -1,7 +1,7 @@
 {
     "name": "@hydrooj/hydrojudge",
     "bin": "bin/hydrojudge.js",
-    "version": "2.3.15",
+    "version": "2.3.16",
     "main": "package.json",
     "author": "undefined <i@undefined.moe>",
     "repository": "https://github.com/hydro-dev/Hydro.git",
@@ -32,4 +32,4 @@
         "build": "tsc",
         "lint": "eslint . --ext ts --fix"
     }
-}
+}
\ No newline at end of file
diff --git a/packages/hydrojudge/src/hosts/hydro.ts b/packages/hydrojudge/src/hosts/hydro.ts
index 79bda7f17..fb2c9a3b3 100644
--- a/packages/hydrojudge/src/hosts/hydro.ts
+++ b/packages/hydrojudge/src/hosts/hydro.ts
@@ -226,6 +226,7 @@ export default class Hydro {
             fs.writeFileSync(path.join(filePath, 'etags'), JSON.stringify(version));
             await this.processData(filePath).catch(noop);
         }
+        fs.writeFileSync(path.join(filePath, 'lastUsage'), new Date().getTime().toString());
         return filePath;
     }
 
diff --git a/packages/hydrojudge/src/hosts/vj4.ts b/packages/hydrojudge/src/hosts/vj4.ts
index b61477325..abf2da961 100644
--- a/packages/hydrojudge/src/hosts/vj4.ts
+++ b/packages/hydrojudge/src/hosts/vj4.ts
@@ -387,12 +387,16 @@ export default class VJ4 {
             try {
                 ver = fs.readFileSync(path.join(filePath, 'version')).toString();
             } catch (e) { /* ignore */ }
-            if (version === ver) return filePath;
+            if (version === ver) {
+                fs.writeFileSync(path.join(filePath, 'lastUsage'), new Date().getTime().toString());
+                return filePath;
+            }
             fs.removeSync(filePath);
         }
         fs.ensureDirSync(domainDir);
         await this.problemData(domainId, pid, filePath, 3, next);
         fs.writeFileSync(path.join(filePath, 'version'), version);
+        fs.writeFileSync(path.join(filePath, 'lastUsage'), new Date().getTime().toString());
         return filePath;
     }
 
diff --git a/packages/hydrojudge/src/service.ts b/packages/hydrojudge/src/service.ts
index 08d79452b..94c5f0818 100644
--- a/packages/hydrojudge/src/service.ts
+++ b/packages/hydrojudge/src/service.ts
@@ -86,6 +86,7 @@ async function postInit() {
             }
         }
         fs.writeFileSync(path.join(filePath, 'etags'), JSON.stringify(version));
+        fs.writeFileSync(path.join(filePath, 'lastUsage'), new Date().getTime().toString());
         await processData(filePath).catch(noop);
         return filePath;
     }