diff --git a/packages/playwright-core/src/client/network.ts b/packages/playwright-core/src/client/network.ts
index 4d36f5dd0a8b1..82286526e8c9f 100644
--- a/packages/playwright-core/src/client/network.ts
+++ b/packages/playwright-core/src/client/network.ts
@@ -137,7 +137,7 @@ export class Request extends ChannelOwner<channels.RequestChannel> implements ap
   }
 
   postData(): string | null {
-    return (this._fallbackOverrides.postDataBuffer || this._initializer.postData)?.toString('utf-8') || null;
+    return (this._fallbackOverrides.postDataBuffer ?? this._initializer.postData)?.toString('utf-8') ?? null;
   }
 
   postDataBuffer(): Buffer | null {
diff --git a/tests/page/page-request-continue.spec.ts b/tests/page/page-request-continue.spec.ts
index 48f9458012b46..a6b4137912db5 100644
--- a/tests/page/page-request-continue.spec.ts
+++ b/tests/page/page-request-continue.spec.ts
@@ -1010,3 +1010,15 @@ it('should not forward Host header on cross-origin redirect', {
   expect(firstHost).toBe(new URL(server.PREFIX).host);
   expect(redirectedHost).toBe(new URL(server.CROSS_PROCESS_PREFIX).host);
 });
+
+it('postData should return empty string when overriding body with empty string', async ({ page, server }) => {
+  await page.goto(server.EMPTY_PAGE);
+  await page.route('**/*', route => {
+    void route.continue({ postData: '' });
+  });
+  const [request] = await Promise.all([
+    page.waitForRequest('**'),
+    page.evaluate(({ url }) => fetch(url, { method: 'POST', body: 'original' }), { url: server.PREFIX + '/sleep.zzz' }),
+  ]);
+  expect(request.postData()).toBe('');
+});