diff --git a/examples/calculator/src/index.tsx b/examples/calculator/src/index.tsx
index 852911990..328248060 100644
--- a/examples/calculator/src/index.tsx
+++ b/examples/calculator/src/index.tsx
@@ -85,7 +85,7 @@ function safeEval(expr: string): string {
     if (tokens.length === 0) return '0';
 
     // Handle initial negative number
-    if (tokens[0] === '-' && tokens.length > 1 && !isNaN(Number(tokens[1]))) {
+    if (tokens[0] === '-' && tokens.length > 1 && !Number.isNaN(Number(tokens[1]))) {
         tokens.splice(0, 2, '-' + tokens[1]);
     }
 
diff --git a/examples/widget-gallery/src/index.ts b/examples/widget-gallery/src/index.ts
index 57b141244..ec688a7fc 100644
--- a/examples/widget-gallery/src/index.ts
+++ b/examples/widget-gallery/src/index.ts
@@ -129,7 +129,7 @@ class WidgetGalleryApp extends Widget {
         }
 
         // Tab switching: 1-6
-        const num = parseInt(event.key);
+        const num = parseInt(event.key, 10);
         if (num >= 1 && num <= 6) {
             this._switchTab(num - 1);
             return true;
diff --git a/packages/ui/src/MultiSelect.ts b/packages/ui/src/MultiSelect.ts
index b4116418f..327e1eee2 100644
--- a/packages/ui/src/MultiSelect.ts
+++ b/packages/ui/src/MultiSelect.ts
@@ -30,7 +30,7 @@ export class MultiSelect extends Widget {
     }
 
     get selectedOptions(): MultiSelectOption[] {
-        return [...this._checked].sort().map(i => this._options[i]);
+        return [...this._checked].sort((a, b) => a - b).map(i => this._options[i]);
     }
     selectNext(): void { if (this._options.length === 0) return; let n = this._cursorIndex + 1; while (n < this._options.length && this._options[n].disabled) n++; if (n < this._options.length) { this._cursorIndex = n; this.markDirty(); } }
     selectPrev(): void { if (this._options.length === 0) return; let n = this._cursorIndex - 1; while (n >= 0 && this._options[n].disabled) n--; if (n >= 0) { this._cursorIndex = n; this.markDirty(); } }