diff --git a/plugins/tsconfig-plugins-base.json b/plugins/tsconfig-plugins-base.json
index 97eae67..b7e9d52 100644
--- a/plugins/tsconfig-plugins-base.json
+++ b/plugins/tsconfig-plugins-base.json
@@ -20,6 +20,7 @@
     "noUnusedLocals": true, /* Report errors on unused locals. */
     "noUnusedParameters": true, /* Report errors on unused parameters. */
     "noImplicitReturns": true, /* Report error when not all code paths in function return a value. */
+    "noImplicitOverride": true,
     "noFallthroughCasesInSwitch": true,/* Report errors for fallthrough cases in switch statement. */
 
     "skipLibCheck": true, /* Do not check node_modules */
diff --git a/polygerrit-ui/app/elements/admin/gr-confirm-delete-item-dialog/gr-confirm-delete-item-dialog.ts b/polygerrit-ui/app/elements/admin/gr-confirm-delete-item-dialog/gr-confirm-delete-item-dialog.ts
index 5a48399..04d3198 100644
--- a/polygerrit-ui/app/elements/admin/gr-confirm-delete-item-dialog/gr-confirm-delete-item-dialog.ts
+++ b/polygerrit-ui/app/elements/admin/gr-confirm-delete-item-dialog/gr-confirm-delete-item-dialog.ts
@@ -45,7 +45,7 @@
   @property({type: String})
   itemTypeName?: string;
 
-  static get styles() {
+  static override get styles() {
     return [
       sharedStyles,
       css`
@@ -57,7 +57,7 @@
     ];
   }
 
-  render() {
+  override render() {
     const item = this.item ?? 'UNKNOWN ITEM';
     const itemTypeName = this.itemTypeName ?? 'UNKNOWN ITEM TYPE';
     return html` <gr-dialog
diff --git a/polygerrit-ui/app/elements/admin/gr-repo-dashboards/gr-repo-dashboards.ts b/polygerrit-ui/app/elements/admin/gr-repo-dashboards/gr-repo-dashboards.ts
index fc7ef4b..7800653 100644
--- a/polygerrit-ui/app/elements/admin/gr-repo-dashboards/gr-repo-dashboards.ts
+++ b/polygerrit-ui/app/elements/admin/gr-repo-dashboards/gr-repo-dashboards.ts
@@ -43,7 +43,7 @@
 
   private readonly restApiService = appContext.restApiService;
 
-  static get styles() {
+  static override get styles() {
     return [
       sharedStyles,
       tableStyles,
@@ -63,7 +63,7 @@
     ];
   }
 
-  render() {
+  override render() {
     return html` <table
       id="list"
       class="genericList ${this._computeLoadingClass(this._loading)}"
@@ -114,7 +114,7 @@
     </table>`;
   }
 
-  updated(changedProperties: PropertyValues) {
+  override updated(changedProperties: PropertyValues) {
     if (changedProperties.has('repo')) {
       this.repoChanged();
     }
diff --git a/polygerrit-ui/app/elements/change-list/gr-user-header/gr-user-header.ts b/polygerrit-ui/app/elements/change-list/gr-user-header/gr-user-header.ts
index bc21dc0..e87b4f9 100644
--- a/polygerrit-ui/app/elements/change-list/gr-user-header/gr-user-header.ts
+++ b/polygerrit-ui/app/elements/change-list/gr-user-header/gr-user-header.ts
@@ -48,7 +48,7 @@
 
   private readonly restApiService = appContext.restApiService;
 
-  static get styles() {
+  static override get styles() {
     return [
       sharedStyles,
       dashboardHeaderStyles,
@@ -63,7 +63,7 @@
     ];
   }
 
-  render() {
+  override render() {
     return html` <gr-avatar
         .account="${this._accountDetails}"
         .imageSize=${100}
@@ -116,7 +116,7 @@
       </div>`;
   }
 
-  updated(changedProperties: PropertyValues) {
+  override updated(changedProperties: PropertyValues) {
     if (changedProperties.has('userId')) {
       this._accountChanged(this.userId);
     }
diff --git a/polygerrit-ui/app/elements/change/gr-commit-info/gr-commit-info.ts b/polygerrit-ui/app/elements/change/gr-commit-info/gr-commit-info.ts
index 1052c91..4326939 100644
--- a/polygerrit-ui/app/elements/change/gr-commit-info/gr-commit-info.ts
+++ b/polygerrit-ui/app/elements/change/gr-commit-info/gr-commit-info.ts
@@ -43,7 +43,7 @@
   @property({type: Object})
   serverConfig: ServerInfo | undefined;
 
-  static get styles() {
+  static override get styles() {
     return [
       sharedStyles,
       css`
@@ -55,7 +55,7 @@
     ];
   }
 
-  render() {
+  override render() {
     return html` <div class="container">
       <a
         target="_blank"
diff --git a/polygerrit-ui/app/elements/change/gr-confirm-submit-dialog/gr-confirm-submit-dialog.ts b/polygerrit-ui/app/elements/change/gr-confirm-submit-dialog/gr-confirm-submit-dialog.ts
index c705319..3ab9c82 100644
--- a/polygerrit-ui/app/elements/change/gr-confirm-submit-dialog/gr-confirm-submit-dialog.ts
+++ b/polygerrit-ui/app/elements/change/gr-confirm-submit-dialog/gr-confirm-submit-dialog.ts
@@ -58,7 +58,7 @@
   @property({type: Boolean})
   _initialised = false;
 
-  static get styles() {
+  static override get styles() {
     return [
       sharedStyles,
       fontStyles,
@@ -154,7 +154,7 @@
     `;
   }
 
-  render() {
+  override render() {
     return html` <gr-dialog
       id="dialog"
       confirm-label="Continue"
diff --git a/polygerrit-ui/app/elements/change/gr-message/gr-message.ts b/polygerrit-ui/app/elements/change/gr-message/gr-message.ts
index b4e85a9..95e4301 100644
--- a/polygerrit-ui/app/elements/change/gr-message/gr-message.ts
+++ b/polygerrit-ui/app/elements/change/gr-message/gr-message.ts
@@ -209,7 +209,7 @@
     this.addEventListener('click', e => this._handleClick(e));
   }
 
-  connectedCallback() {
+  override connectedCallback() {
     super.connectedCallback();
     this.restApiService.getConfig().then(config => {
       this.config = config;
diff --git a/polygerrit-ui/app/elements/core/gr-account-dropdown/gr-account-dropdown.ts b/polygerrit-ui/app/elements/core/gr-account-dropdown/gr-account-dropdown.ts
index 0dbe823a..1517d36 100644
--- a/polygerrit-ui/app/elements/core/gr-account-dropdown/gr-account-dropdown.ts
+++ b/polygerrit-ui/app/elements/core/gr-account-dropdown/gr-account-dropdown.ts
@@ -76,7 +76,7 @@
     super.disconnectedCallback();
   }
 
-  static get styles() {
+  static override get styles() {
     return [
       sharedStyles,
       css`
@@ -92,7 +92,7 @@
     ];
   }
 
-  render() {
+  override render() {
     // To pass CSS mixins for @apply to Polymer components, they need to appear
     // in <style> inside the template.
     const customStyle = html`
diff --git a/polygerrit-ui/app/elements/core/gr-search-bar/gr-search-bar.ts b/polygerrit-ui/app/elements/core/gr-search-bar/gr-search-bar.ts
index 7b12b1117..240bb22 100644
--- a/polygerrit-ui/app/elements/core/gr-search-bar/gr-search-bar.ts
+++ b/polygerrit-ui/app/elements/core/gr-search-bar/gr-search-bar.ts
@@ -204,7 +204,7 @@
     this.query = (input: string) => this._getSearchSuggestions(input);
   }
 
-  connectedCallback() {
+  override connectedCallback() {
     super.connectedCallback();
     this.restApiService.getConfig().then((serverConfig?: ServerInfo) => {
       const mergeability =
diff --git a/polygerrit-ui/app/elements/diff/gr-apply-fix-dialog/gr-apply-fix-dialog.ts b/polygerrit-ui/app/elements/diff/gr-apply-fix-dialog/gr-apply-fix-dialog.ts
index 1c25755..f5072b9 100644
--- a/polygerrit-ui/app/elements/diff/gr-apply-fix-dialog/gr-apply-fix-dialog.ts
+++ b/polygerrit-ui/app/elements/diff/gr-apply-fix-dialog/gr-apply-fix-dialog.ts
@@ -150,7 +150,7 @@
     });
   }
 
-  connectedCallback() {
+  override connectedCallback() {
     super.connectedCallback();
     this.refitOverlay = () => {
       // re-center the dialog as content changed
diff --git a/polygerrit-ui/app/elements/plugins/gr-plugin-host/gr-plugin-host.ts b/polygerrit-ui/app/elements/plugins/gr-plugin-host/gr-plugin-host.ts
index 988366c..7fee4a0 100644
--- a/polygerrit-ui/app/elements/plugins/gr-plugin-host/gr-plugin-host.ts
+++ b/polygerrit-ui/app/elements/plugins/gr-plugin-host/gr-plugin-host.ts
@@ -37,7 +37,7 @@
     getPluginLoader().loadPlugins(pluginsPending);
   }
 
-  updated(changedProperties: PropertyValues<GrPluginHost>) {
+  override updated(changedProperties: PropertyValues<GrPluginHost>) {
     if (changedProperties.has('config') && this.config) {
       this._configChanged(this.config);
     }
diff --git a/polygerrit-ui/app/elements/settings/gr-agreements-list/gr-agreements-list.ts b/polygerrit-ui/app/elements/settings/gr-agreements-list/gr-agreements-list.ts
index eca38d9..a972db3 100644
--- a/polygerrit-ui/app/elements/settings/gr-agreements-list/gr-agreements-list.ts
+++ b/polygerrit-ui/app/elements/settings/gr-agreements-list/gr-agreements-list.ts
@@ -41,7 +41,7 @@
     });
   }
 
-  static get styles() {
+  static override get styles() {
     return [
       sharedStyles,
       css`
@@ -71,7 +71,7 @@
     `;
   }
 
-  render() {
+  override render() {
     return html` <div class="gr-form-styles">
       <table id="agreements">
         <thead>
diff --git a/polygerrit-ui/app/elements/settings/gr-http-password/gr-http-password.ts b/polygerrit-ui/app/elements/settings/gr-http-password/gr-http-password.ts
index 6354c9a..c62cff4 100644
--- a/polygerrit-ui/app/elements/settings/gr-http-password/gr-http-password.ts
+++ b/polygerrit-ui/app/elements/settings/gr-http-password/gr-http-password.ts
@@ -75,7 +75,7 @@
     return Promise.all(promises);
   }
 
-  static get styles() {
+  static override get styles() {
     return [
       sharedStyles,
       formStyles,
@@ -113,7 +113,7 @@
     ];
   }
 
-  render() {
+  override render() {
     return html` <div class="gr-form-styles">
         <div ?hidden=${this._passwordUrl}>
           <section>
diff --git a/polygerrit-ui/app/elements/shared/gr-alert/gr-alert.ts b/polygerrit-ui/app/elements/shared/gr-alert/gr-alert.ts
index 895c99b..c38c196 100644
--- a/polygerrit-ui/app/elements/shared/gr-alert/gr-alert.ts
+++ b/polygerrit-ui/app/elements/shared/gr-alert/gr-alert.ts
@@ -30,7 +30,7 @@
 
 @customElement('gr-alert')
 export class GrAlert extends LitElement {
-  static get styles() {
+  static override get styles() {
     return [
       sharedStyles,
       css`
@@ -93,7 +93,7 @@
     >`;
   }
 
-  render() {
+  override render() {
     // To pass CSS mixins for @apply to Polymer components, they need to appear
     // in <style> inside the template.
     const style = html`<style>
diff --git a/polygerrit-ui/app/elements/shared/gr-file-status-chip/gr-file-status-chip.ts b/polygerrit-ui/app/elements/shared/gr-file-status-chip/gr-file-status-chip.ts
index 0f94b11..3f759b5 100644
--- a/polygerrit-ui/app/elements/shared/gr-file-status-chip/gr-file-status-chip.ts
+++ b/polygerrit-ui/app/elements/shared/gr-file-status-chip/gr-file-status-chip.ts
@@ -36,7 +36,7 @@
   @property({type: Object})
   file?: NormalizedFileInfo;
 
-  static get styles() {
+  static override get styles() {
     return [
       sharedStyles,
       css`
@@ -65,7 +65,7 @@
     ];
   }
 
-  render() {
+  override render() {
     return html` <span
       class="${this._computeStatusClass(this.file)}"
       tabindex="0"
diff --git a/polygerrit-ui/app/elements/shared/gr-hovercard-account/gr-hovercard-account.ts b/polygerrit-ui/app/elements/shared/gr-hovercard-account/gr-hovercard-account.ts
index a329736..b789bee 100644
--- a/polygerrit-ui/app/elements/shared/gr-hovercard-account/gr-hovercard-account.ts
+++ b/polygerrit-ui/app/elements/shared/gr-hovercard-account/gr-hovercard-account.ts
@@ -96,7 +96,7 @@
     this.reporting = appContext.reportingService;
   }
 
-  connectedCallback() {
+  override connectedCallback() {
     super.connectedCallback();
     this.restApiService.getConfig().then(config => {
       this._config = config;
diff --git a/polygerrit-ui/app/elements/shared/gr-linked-chip/gr-linked-chip.ts b/polygerrit-ui/app/elements/shared/gr-linked-chip/gr-linked-chip.ts
index 5bf5a8f..9c6d947 100644
--- a/polygerrit-ui/app/elements/shared/gr-linked-chip/gr-linked-chip.ts
+++ b/polygerrit-ui/app/elements/shared/gr-linked-chip/gr-linked-chip.ts
@@ -50,7 +50,7 @@
   @property({type: Number})
   limit?: number;
 
-  static get styles() {
+  static override get styles() {
     return [
       sharedStyles,
       css`
@@ -84,7 +84,7 @@
     ];
   }
 
-  render() {
+  override render() {
     // To pass CSS mixins for @apply to Polymer components, they need to appear
     // in <style> inside the template.
     const customStyle = html`
diff --git a/polygerrit-ui/app/elements/shared/gr-page-nav/gr-page-nav.ts b/polygerrit-ui/app/elements/shared/gr-page-nav/gr-page-nav.ts
index b2477dd..423a1a8 100644
--- a/polygerrit-ui/app/elements/shared/gr-page-nav/gr-page-nav.ts
+++ b/polygerrit-ui/app/elements/shared/gr-page-nav/gr-page-nav.ts
@@ -53,7 +53,7 @@
     this.bodyScrollHandler = () => this._handleBodyScroll();
   }
 
-  connectedCallback() {
+  override connectedCallback() {
     super.connectedCallback();
     window.addEventListener('scroll', this.bodyScrollHandler);
   }
diff --git a/polygerrit-ui/app/elements/shared/gr-vote-chip/gr-vote-chip.ts b/polygerrit-ui/app/elements/shared/gr-vote-chip/gr-vote-chip.ts
index 73ca99d..2fd3fb9 100644
--- a/polygerrit-ui/app/elements/shared/gr-vote-chip/gr-vote-chip.ts
+++ b/polygerrit-ui/app/elements/shared/gr-vote-chip/gr-vote-chip.ts
@@ -45,7 +45,7 @@
 
   private readonly flagsService = appContext.flagsService;
 
-  static get styles() {
+  static override get styles() {
     return [
       css`
         .vote-chip.max {
@@ -106,7 +106,7 @@
     ];
   }
 
-  render() {
+  override render() {
     if (!this.flagsService.isEnabled(KnownExperimentId.SUBMIT_REQUIREMENTS_UI))
       return;
     if (!this.vote?.value) return;
diff --git a/polygerrit-ui/app/tsconfig.json b/polygerrit-ui/app/tsconfig.json
index 9516dce..7b01226 100644
--- a/polygerrit-ui/app/tsconfig.json
+++ b/polygerrit-ui/app/tsconfig.json
@@ -25,6 +25,7 @@
     "noUnusedLocals": true, /* Report errors on unused locals. */
     "noUnusedParameters": true, /* Report errors on unused parameters. */
     "noImplicitReturns": true, /* Report error when not all code paths in function return a value. */
+    "noImplicitOverride": true,
     "noFallthroughCasesInSwitch": true,/* Report errors for fallthrough cases in switch statement. */
 
     "skipLibCheck": true, /* Do not check node_modules */