diff --git a/packages/playwright/src/plugins/webServerPlugin.ts b/packages/playwright/src/plugins/webServerPlugin.ts
index 5eda8ee822..0af0b90bbf 100644
--- a/packages/playwright/src/plugins/webServerPlugin.ts
+++ b/packages/playwright/src/plugins/webServerPlugin.ts
@@ -101,6 +101,8 @@ export class WebServerPlugin implements TestRunnerPlugin {
         timeout = this._options.kill.SIGINT;
       }
       if ('SIGTERM' in this._options.kill && typeof this._options.kill.SIGTERM === 'number') {
+        if (signal)
+          throw new Error('Only one of SIGINT or SIGTERM can be specified in config.webServer.kill');
         signal = 'SIGTERM';
         timeout = this._options.kill.SIGTERM;
       }
diff --git a/tests/playwright-test/web-server.spec.ts b/tests/playwright-test/web-server.spec.ts
index f3c3d772f0..e5e42f2643 100644
--- a/tests/playwright-test/web-server.spec.ts
+++ b/tests/playwright-test/web-server.spec.ts
@@ -804,4 +804,11 @@ test.describe('kill option', () => {
 
     expect(testProcess.outputLines({ prefix: '[WebServer] ' })).toEqual(['webserver received SIGINT but stubbornly refuses to wind down']);
   });
+
+  test('throws when mixed', async ({ interactWithTestRunner }) => {
+    const testProcess = await interactWithTestRunner(files({ kill: { SIGINT: 500, SIGTERM: 500 } }), { workers: 1 });
+    await testProcess.exited;
+
+    expect(testProcess.output).toContain('Only one of SIGINT or SIGTERM can be specified in config.webServer.kill');
+  });
 });