diff --git a/packages/void/test/unit/island-css-rewrite.test.ts b/packages/void/test/unit/island-css-rewrite.test.ts
index bf3e4a038..2d62536aa 100644
--- a/packages/void/test/unit/island-css-rewrite.test.ts
+++ b/packages/void/test/unit/island-css-rewrite.test.ts
@@ -1,30 +1,35 @@
+import { resolve } from "node:path";
+import { normalizePath } from "vite";
 import { describe, it, expect } from "vitest";
 import { rewriteCssImportForVirtualModule } from "../../src/pages/islands-plugin";
 
+/** Resolve a POSIX-style absolute path to a platform-correct path with forward slashes. */
+const p = (posix: string) => normalizePath(resolve(posix));
+
 describe("rewriteCssImportForVirtualModule", () => {
   it("rewrites relative CSS import to absolute path", () => {
     const result = rewriteCssImportForVirtualModule(
       'import "./global.css"',
       "./global.css",
-      "/project/pages/layout.tsx",
+      p("/project/pages/layout.tsx"),
     );
-    expect(result).toBe('import "/project/pages/global.css";');
+    expect(result).toBe(`import "${p("/project/pages/global.css")}";`);
   });
 
   it("rewrites parent-relative CSS import to absolute path", () => {
     const result = rewriteCssImportForVirtualModule(
       'import "../styles/theme.css"',
       "../styles/theme.css",
-      "/project/pages/blog/index.tsx",
+      p("/project/pages/blog/index.tsx"),
     );
-    expect(result).toBe('import "/project/pages/styles/theme.css";');
+    expect(result).toBe(`import "${p("/project/pages/styles/theme.css")}";`);
   });
 
   it("preserves bare specifiers (package imports)", () => {
     const result = rewriteCssImportForVirtualModule(
       'import "@void/md/theme.css"',
       "@void/md/theme.css",
-      "/project/pages/layout.tsx",
+      p("/project/pages/layout.tsx"),
     );
     expect(result).toBe('import "@void/md/theme.css";');
   });
@@ -33,7 +38,7 @@ describe("rewriteCssImportForVirtualModule", () => {
     const result = rewriteCssImportForVirtualModule(
       'import "/absolute/path/style.css"',
       "/absolute/path/style.css",
-      "/project/pages/layout.tsx",
+      p("/project/pages/layout.tsx"),
     );
     expect(result).toBe('import "/absolute/path/style.css";');
   });
@@ -42,7 +47,7 @@ describe("rewriteCssImportForVirtualModule", () => {
     const result = rewriteCssImportForVirtualModule(
       '  import "some-lib/styles.css"  ',
       "some-lib/styles.css",
-      "/project/pages/layout.tsx",
+      p("/project/pages/layout.tsx"),
     );
     expect(result).toBe('import "some-lib/styles.css";');
   });
@@ -52,10 +57,10 @@ describe("rewriteCssImportForVirtualModule", () => {
     const result = rewriteCssImportForVirtualModule(
       'import "./card.css"',
       "./card.css",
-      "/project/pages/components/deep/Card.tsx",
+      p("/project/pages/components/deep/Card.tsx"),
     );
     // Should always use forward slashes regardless of OS
     expect(result).not.toContain("\\");
-    expect(result).toBe('import "/project/pages/components/deep/card.css";');
+    expect(result).toBe(`import "${p("/project/pages/components/deep/card.css")}";`);
   });
 });