diff --git a/src/util.ts b/src/util.ts
index 26018b85..9d48359b 100644
--- a/src/util.ts
+++ b/src/util.ts
@@ -48,10 +48,6 @@ export function runExitHandlers() {
 
 const exitSignals = ['exit', 'SIGINT', 'SIGTERM'];
 exitSignals.forEach((sig) => {
-  // https://github.com/vitest-dev/vitest/issues/7236
-  if (import.meta.env?.VITEST) {
-    return;
-  }
   process.once(sig, (signal?: string | number, exitCode?: number) => {
     runExitHandlers();
     if (process.exitCode === undefined) {
diff --git a/tests/command-util.ts b/tests/command-util.ts
index 0a2cfbae..3b21b716 100644
--- a/tests/command-util.ts
+++ b/tests/command-util.ts
@@ -32,7 +32,13 @@ export const runCommand = async (
     cwd,
     config,
     logLevel = 'silent',
-  }: { cwd: string; config?: VivliostyleConfigSchema; logLevel?: LogLevel },
+    port,
+  }: {
+    cwd: string;
+    config?: VivliostyleConfigSchema;
+    logLevel?: LogLevel;
+    port?: number;
+  },
 ): Promise<ViteDevServer | void> => {
   let inlineConfig = parseFlagsToInlineConfig(
     ['vivliostyle', command, ...args],
@@ -42,7 +48,7 @@ export const runCommand = async (
       preview: setupPreviewParserProgram,
     }[command],
   );
-  inlineConfig = { ...inlineConfig, configData: config, cwd, logLevel };
+  inlineConfig = { ...inlineConfig, configData: config, cwd, logLevel, port };
   return await { init, build, preview }[command](inlineConfig);
 };
 
diff --git a/tests/pdf.test.ts b/tests/pdf.test.ts
index 73896505..7a50e51c 100644
--- a/tests/pdf.test.ts
+++ b/tests/pdf.test.ts
@@ -8,6 +8,7 @@ describe('pdf output', () => {
       ['build', '-s', 'A4', '-o', '.vs-pdf/test.pdf', 'index.html'],
       {
         cwd: resolveFixture('wood'),
+        port: 23000,
       },
     );
 
diff --git a/vite.config.ts b/vite.config.ts
index 28850505..01c0e063 100644
--- a/vite.config.ts
+++ b/vite.config.ts
@@ -16,5 +16,6 @@ export default defineConfig({
       NO_COLOR: 'true',
     },
     clearMocks: true,
+    pool: 'threads',
   },
 });