diff --git a/ui/package.json b/ui/package.json
index e27b729..4c8a36a 100644
--- a/ui/package.json
+++ b/ui/package.json
@@ -66,7 +66,7 @@
     "puppeteer": "^17.1.3",
     "rimraf": "^3.0.2",
     "tree-kill": "^1.2.0",
-    "typescript": "4.0.2",
+    "typescript": "^5.9.2",
     "wait-on": "^5.3.0"
   },
   "eslintConfig": {
diff --git a/ui/src/application/AddApplicationDialog.tsx b/ui/src/application/AddApplicationDialog.tsx
index dce6b92..b0ad8f7 100644
--- a/ui/src/application/AddApplicationDialog.tsx
+++ b/ui/src/application/AddApplicationDialog.tsx
@@ -89,7 +89,10 @@ export default class AddDialog extends Component<IProps, IState> {
         );
     }
 
-    private handleChange(propertyName: string, event: React.ChangeEvent<HTMLInputElement>) {
+    private handleChange(
+        propertyName: 'description' | 'name',
+        event: React.ChangeEvent<HTMLInputElement>
+    ) {
         const state = this.state;
         state[propertyName] = event.target.value;
         this.setState(state);
diff --git a/ui/src/application/UpdateApplicationDialog.tsx b/ui/src/application/UpdateApplicationDialog.tsx
index ed04022..d5c7e88 100644
--- a/ui/src/application/UpdateApplicationDialog.tsx
+++ b/ui/src/application/UpdateApplicationDialog.tsx
@@ -101,7 +101,10 @@ export default class UpdateDialog extends Component<IProps, IState> {
         );
     }
 
-    private handleChange(propertyName: string, event: React.ChangeEvent<HTMLInputElement>) {
+    private handleChange(
+        propertyName: 'name' | 'description',
+        event: React.ChangeEvent<HTMLInputElement>
+    ) {
         const state = this.state;
         state[propertyName] = event.target.value;
         this.setState(state);
diff --git a/ui/src/client/AddClientDialog.tsx b/ui/src/client/AddClientDialog.tsx
index 3249b60..7324993 100644
--- a/ui/src/client/AddClientDialog.tsx
+++ b/ui/src/client/AddClientDialog.tsx
@@ -63,7 +63,7 @@ export default class AddDialog extends Component<IProps, {name: string}> {
         );
     }
 
-    private handleChange(propertyName: string, event: React.ChangeEvent<HTMLInputElement>) {
+    private handleChange(propertyName: 'name', event: React.ChangeEvent<HTMLInputElement>) {
         const state = this.state;
         state[propertyName] = event.target.value;
         this.setState(state);
diff --git a/ui/src/client/UpdateClientDialog.tsx b/ui/src/client/UpdateClientDialog.tsx
index 214a7c2..316c079 100644
--- a/ui/src/client/UpdateClientDialog.tsx
+++ b/ui/src/client/UpdateClientDialog.tsx
@@ -78,8 +78,8 @@ export default class UpdateDialog extends Component<IProps, IState> {
         );
     }
 
-    private handleChange(propertyName: string, event: React.ChangeEvent<HTMLInputElement>) {
-        const state = {};
+    private handleChange(propertyName: 'name', event: React.ChangeEvent<HTMLInputElement>) {
+        const state = this.state;
         state[propertyName] = event.target.value;
         this.setState(state);
     }
diff --git a/ui/src/message/MessagesStore.ts b/ui/src/message/MessagesStore.ts
index 136d2a9..24ff431 100644
--- a/ui/src/message/MessagesStore.ts
+++ b/ui/src/message/MessagesStore.ts
@@ -136,15 +136,17 @@ export class MessagesStore {
         }
     };
 
-    private getUnCached = (appId: number): Array<IMessage & {image: string | null}> => {
-        const appToImage = this.appStore
+    private getUnCached = (appId: number): Array<IMessage> => {
+        const appToImage: Partial<Record<string, string>> = this.appStore
             .getItems()
             .reduce((all, app) => ({...all, [app.id]: app.image}), {});
 
-        return this.stateOf(appId, false).messages.map((message: IMessage) => ({
-            ...message,
-            image: appToImage[message.appid] || null,
-        }));
+        return this.stateOf(appId, false).messages.map(
+            (message: IMessage): IMessage => ({
+                ...message,
+                image: appToImage[message.appid],
+            })
+        );
     };
 
     public get = createTransformer(this.getUnCached);
diff --git a/ui/src/message/extras.ts b/ui/src/message/extras.ts
index 724a744..976d575 100644
--- a/ui/src/message/extras.ts
+++ b/ui/src/message/extras.ts
@@ -7,9 +7,7 @@ export enum RenderMode {
 
 export const contentType = (extras?: IMessageExtras): RenderMode => {
     const type = extract(extras, 'client::display', 'contentType');
-    const valid = Object.keys(RenderMode)
-        .map((k) => RenderMode[k])
-        .some((mode) => mode === type);
+    const valid = Object.values(RenderMode).includes(type);
     return valid ? type : RenderMode.Plain;
 };
 
diff --git a/ui/src/tests/plugin.test.ts b/ui/src/tests/plugin.test.ts
index 792136b..852d471 100644
--- a/ui/src/tests/plugin.test.ts
+++ b/ui/src/tests/plugin.test.ts
@@ -172,6 +172,9 @@ describe('plugin', () => {
                 await inDetailPage(1, async () => {
                     await page.waitForSelector('.displayer a');
                     const hook = await page.$eval('.displayer a', (el) => el.getAttribute('href'));
+                    if (!hook) {
+                        throw 'href not found';
+                    }
                     await axios.get(hook);
                 });
             });
diff --git a/ui/src/tests/setup.ts b/ui/src/tests/setup.ts
index 4f7e5bd..293b304 100644
--- a/ui/src/tests/setup.ts
+++ b/ui/src/tests/setup.ts
@@ -50,7 +50,9 @@ export const newTest = async (pluginsDir = ''): Promise<GotifyTest> => {
         close: async () => {
             await Promise.all([
                 browser.close(),
-                new Promise((resolve) => kill(gotifyInstance.pid!, 'SIGKILL', () => resolve())),
+                new Promise((resolve) =>
+                    kill(gotifyInstance.pid!, 'SIGKILL', () => resolve(undefined))
+                ),
             ]);
             rimraf.sync(gotifyFile, {maxBusyTries: 8});
         },
diff --git a/ui/src/tests/utils.ts b/ui/src/tests/utils.ts
index 75c73c2..8330cf9 100644
--- a/ui/src/tests/utils.ts
+++ b/ui/src/tests/utils.ts
@@ -59,7 +59,7 @@ export const waitForExists = async (page: Page, selector: string, text: string):
 export const clearField = async (element: ElementHandle | Page, selector: string) => {
     const elementHandle = await element.$(selector);
     if (!elementHandle) {
-        throw "element handle not set"
+        throw 'element handle not set';
     }
     await elementHandle.click();
     await elementHandle.focus();
diff --git a/ui/src/user/AddEditUserDialog.tsx b/ui/src/user/AddEditUserDialog.tsx
index 731fabf..fdf93d8 100644
--- a/ui/src/user/AddEditUserDialog.tsx
+++ b/ui/src/user/AddEditUserDialog.tsx
@@ -110,13 +110,13 @@ export default class AddEditDialog extends Component<IProps, IState> {
         );
     }
 
-    private handleChange(propertyName: string, event: ChangeEvent<HTMLInputElement>) {
+    private handleChange(propertyName: 'name' | 'pass', event: ChangeEvent<HTMLInputElement>) {
         const state = this.state;
         state[propertyName] = event.target.value;
         this.setState(state);
     }
 
-    private handleChecked(propertyName: string, event: ChangeEvent<HTMLInputElement>) {
+    private handleChecked(propertyName: 'admin', event: ChangeEvent<HTMLInputElement>) {
         const state = this.state;
         state[propertyName] = event.target.checked;
         this.setState(state);
diff --git a/ui/src/user/Register.tsx b/ui/src/user/Register.tsx
index 7e0dfa4..b5309f5 100644
--- a/ui/src/user/Register.tsx
+++ b/ui/src/user/Register.tsx
@@ -96,7 +96,7 @@ export default class RegistrationDialog extends Component<IProps, IState> {
         );
     }
 
-    private handleChange(propertyName: string, event: ChangeEvent<HTMLInputElement>) {
+    private handleChange(propertyName: keyof IState, event: ChangeEvent<HTMLInputElement>) {
         const state = this.state;
         state[propertyName] = event.target.value;
         this.setState(state);
diff --git a/ui/yarn.lock b/ui/yarn.lock
index 11b5256..fac81a5 100644
--- a/ui/yarn.lock
+++ b/ui/yarn.lock
@@ -3827,10 +3827,10 @@ typeface-roboto@1.1.13:
   resolved "https://registry.yarnpkg.com/typeface-roboto/-/typeface-roboto-1.1.13.tgz#9c4517cb91e311706c74823e857b4bac9a764ae5"
   integrity sha512-YXvbd3a1QTREoD+FJoEkl0VQNJoEjewR2H11IjVv4bp6ahuIcw0yyw/3udC4vJkHw3T3cUh85FTg8eWef3pSaw==
 
-typescript@4.0.2:
-  version "4.0.2"
-  resolved "https://registry.yarnpkg.com/typescript/-/typescript-4.0.2.tgz#7ea7c88777c723c681e33bf7988be5d008d05ac2"
-  integrity sha512-e4ERvRV2wb+rRZ/IQeb3jm2VxBsirQLpQhdxplZ2MEzGvDkkMmPglecnNDfSUBivMjP93vRbngYYDQqQ/78bcQ==
+typescript@^5.9.2:
+  version "5.9.2"
+  resolved "https://registry.yarnpkg.com/typescript/-/typescript-5.9.2.tgz#d93450cddec5154a2d5cabe3b8102b83316fb2a6"
+  integrity sha512-CWBzXQrc/qOkhidw1OzBTQuYRbfyxDXJMVJ1XNwUHGROVmuaeiEm3OslpZ1RV96d7SKKjZKrSJu3+t/xlw3R9A==
 
 ua-parser-js@^0.7.30:
   version "0.7.31"