diff --git a/tsconfig.json b/tsconfig.json
index ca9ec1e..8405d31 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -38,6 +38,8 @@
     "src/**/*.js",
     "src/**/*.svelte",
     "src/**/*.d.ts",
+    "vitest.config*.ts",
+    "vitest.setup*.ts",
     "vitest.types.d.ts"
   ],
   "exclude": [
diff --git a/vitest.setup.jsdom.ts b/vitest.setup.jsdom.ts
index 6f9a136..0aa5e51 100644
--- a/vitest.setup.jsdom.ts
+++ b/vitest.setup.jsdom.ts
@@ -17,7 +17,7 @@ Element.prototype.animate = vi.fn().mockReturnValue({
 });
 
 // jsdom lacks SVG geometry methods
-SVGElement.prototype.getTotalLength = vi.fn(() => 0);
+(SVGElement.prototype as any).getTotalLength = vi.fn(() => 0);
 
 // Robust localStorage mock for jsdom environment
 const localStorageMock = (() => {