diff --git a/apps/drained/app.ts b/apps/drained/app.ts
index cfac5bacf..65966ed6e 100644
--- a/apps/drained/app.ts
+++ b/apps/drained/app.ts
@@ -1,6 +1,7 @@
 const app = "drained";
 
 // from boot.js
+declare var drainedInterval: number | undefined;
 if(typeof drainedInterval !== "undefined")
   drainedInterval = clearInterval(drainedInterval) as undefined;
 
diff --git a/apps/drained/boot.ts b/apps/drained/boot.ts
index ceba64bad..6252edafb 100644
--- a/apps/drained/boot.ts
+++ b/apps/drained/boot.ts
@@ -1,4 +1,4 @@
-const { battery = 5, interval = 10 } = require("Storage")
+const { battery = 5, interval = 10 }: DrainedSettings = require("Storage")
   .readJSON(`${app}.setting.json`, true) || {};
 
 let drainedInterval: number | undefined = setInterval(() => {
diff --git a/apps/drained/settings.ts b/apps/drained/settings.ts
index 77ee800f8..f763a8fe7 100644
--- a/apps/drained/settings.ts
+++ b/apps/drained/settings.ts
@@ -1,8 +1,13 @@
+type DrainedSettings = {
+  battery?: number,
+  interval?: number,
+};
+
 ((back: () => void) => {
   const SETTINGS_FILE = "drained.setting.json";
 
   const storage = require("Storage")
-  const settings = storage.readJSON(SETTINGS_FILE, true) || {};
+  const settings: DrainedSettings = storage.readJSON(SETTINGS_FILE, true) || {};
   settings.battery ??= 5;
   settings.interval ??= 10;