diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index b249002..187e2b5 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -14,8 +14,12 @@ permissions:
 
 jobs:
   tests:
-    name: Build and test
-    runs-on: ubuntu-latest
+    name: Build and test (${{ matrix.os }})
+    runs-on: ${{ matrix.os }}
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [ubuntu-latest, windows-latest]
     steps:
       - uses: actions/checkout@v4
 
diff --git a/src/vite/index.ts b/src/vite/index.ts
index 4279b50..3bc19fa 100644
--- a/src/vite/index.ts
+++ b/src/vite/index.ts
@@ -319,12 +319,12 @@ export function fileRoutes(options: FileRoutesOptions = {}): PluginOption[] {
               // plus the `src` lazy refs already expose.
               if (!codeSplitting) {
                 return {
-                  src: relative(root, buildId),
+                  src: normalizePath(relative(root, buildId)),
                   require: `_$() => (${js.addNamespaceImport(buildId)})$_`
                 };
               }
               return {
-                src: relative(root, buildId),
+                src: normalizePath(relative(root, buildId)),
                 build: isBuild ? `_$() => import('${buildId}')$_` : undefined,
                 import: `_$() => import('${buildId}')$_`
               };
diff --git a/test/vite.spec.ts b/test/vite.spec.ts
index d0af478..302d012 100644
--- a/test/vite.spec.ts
+++ b/test/vite.spec.ts
@@ -85,6 +85,21 @@ describe("fileRoutes vite plugin", () => {
     expect(code.match(/pick=default&pick=\$css&lang\.tsx'\)/g)?.length).toBe(2);
   });
 
+  it("serializes lazy-ref src values with forward slashes", async () => {
+    const directory = createRouteTree({
+      "index.tsx": "export default () => <h1>Home</h1>;"
+    });
+
+    const split = await loadVirtualModule(directory);
+    const eager = await loadWith(createPlugin(directory, { codeSplitting: false }), directory);
+
+    // `src` is matched against Vite's manifest keys, which are always posix,
+    // so it must not carry the platform separator node:path emits on Windows
+    const src = '"src":"src/routes/index.tsx?pick=default&pick=$css&lang.tsx"';
+    expect(split).toContain(src);
+    expect(eager).toContain(src);
+  });
+
   it("resolves only the virtual module id", async () => {
     const [plugin] = fileRoutes() as any[];
     expect(moduleId).toBe("virtual:file-routes");