diff --git a/src/tools/esbuild/create-federation-tsconfig.spec.ts b/src/tools/esbuild/create-federation-tsconfig.spec.ts
index 0b68bc9..b228695 100644
--- a/src/tools/esbuild/create-federation-tsconfig.spec.ts
+++ b/src/tools/esbuild/create-federation-tsconfig.spec.ts
@@ -1,4 +1,5 @@
 import fs from 'fs';
+import path from 'path';
 import JSON5 from 'json5';
 
 import { updateFederationTsConfig } from './create-federation-tsconfig.js';
@@ -61,6 +62,22 @@ describe('updateFederationTsConfig', () => {
     expect(written.include).toEqual(['src/a.ts']);
   });
 
+  it('normalizes OS-specific backslash separators to forward slashes', () => {
+    vi.mocked(fs.existsSync).mockReturnValue(true);
+    vi.mocked(fs.readFileSync).mockReturnValue(JSON5.stringify({ include: [] }) as never);
+    // Simulate Windows: path.relative returns single-backslash separators.
+    const relativeSpy = vi
+      .spyOn(path, 'relative')
+      .mockReturnValue('..\\libs\\shared\\src\\index.ts');
+
+    updateFederationTsConfig('/ws', 'tsconfig.fed.json', [entry('/libs/shared/src/index.ts')]);
+
+    const written = JSON.parse(String(vi.mocked(fs.writeFileSync).mock.calls[0]![1]));
+    expect(written.include).toEqual(['../libs/shared/src/index.ts']);
+
+    relativeSpy.mockRestore();
+  });
+
   it('does not write when the resulting config is unchanged', () => {
     vi.mocked(fs.existsSync).mockReturnValue(true);
     vi.mocked(fs.readFileSync).mockReturnValue(JSON5.stringify({ include: ['src/a.ts'] }) as never);
diff --git a/src/tools/esbuild/create-federation-tsconfig.ts b/src/tools/esbuild/create-federation-tsconfig.ts
index 5cb4eaa..9a59432 100644
--- a/src/tools/esbuild/create-federation-tsconfig.ts
+++ b/src/tools/esbuild/create-federation-tsconfig.ts
@@ -18,7 +18,7 @@ export function updateFederationTsConfig(
 
   const filtered = entryPoints
     .filter(ep => !ep.fileName.startsWith('.'))
-    .map(ep => path.relative(tsconfigDir, ep.fileName).replace(/\\\\/g, '/'));
+    .map(ep => path.relative(tsconfigDir, ep.fileName).replace(/\\/g, '/'));
 
   if (filtered.length === 0) {
     return;