diff --git a/src/needs-parens.mjs b/src/needs-parens.mjs
index 2bd051fc0..1fa215282 100644
--- a/src/needs-parens.mjs
+++ b/src/needs-parens.mjs
@@ -128,9 +128,14 @@ function needsParens(path, options) {
     }
     case "clone":
     case "new": {
+      // Parentheses around `new` with member access are only optional on
+      // PHP >= 8.4. When the PHP version is just a guess (default "auto"
+      // without a composer.json), stay conservative and keep them so the
+      // output stays valid on older PHP versions (see #2440).
       const requiresParens =
         node.kind === "clone" ||
-        (node.kind === "new" && options.phpVersion < 8.4);
+        (node.kind === "new" &&
+          (options.phpVersion < 8.4 || options.phpVersionIsGuessed));
       switch (parent.kind) {
         case "propertylookup":
         case "nullsafepropertylookup":
diff --git a/src/options.mjs b/src/options.mjs
index e650f85ad..34a423ab9 100644
--- a/src/options.mjs
+++ b/src/options.mjs
@@ -87,8 +87,13 @@ export function resolvePhpVersion(options) {
     return;
   }
   if (options.phpVersion === "auto") {
-    options.phpVersion =
-      getComposerPhpVersion() ?? LATEST_SUPPORTED_PHP_VERSION;
+    const composerVersion = getComposerPhpVersion();
+    options.phpVersion = composerVersion ?? LATEST_SUPPORTED_PHP_VERSION;
+    // Without a composer.json pinning a PHP version, "auto" falls back to
+    // the latest supported version, which is only a guess. Remember that
+    // so the printer stays conservative and never emits syntax that is
+    // invalid on older PHP versions (see #2440).
+    options.phpVersionIsGuessed = composerVersion === null;
   } else if (options.phpVersion === "composer") {
     const v = getComposerPhpVersion();
     if (v === null) {
diff --git a/tests/assign/__snapshots__/jsfmt.spec.mjs.snap b/tests/assign/__snapshots__/jsfmt.spec.mjs.snap
index 78d9bd542..b9d4aef69 100644
--- a/tests/assign/__snapshots__/jsfmt.spec.mjs.snap
+++ b/tests/assign/__snapshots__/jsfmt.spec.mjs.snap
@@ -233,7 +233,7 @@ $veryVeryVeryVeryVeryVeryVeryVeryVeryVeryVeryLongVariable = $veryVeryVeryVeryVer
 $obj->property = $obj->oneProperty = $obj->twoPeroperty = 0;
 $obj->veryVeryVeryVeryVeryVeryVeryVeryVeryVeryVeryLongProperty = $obj->veryVeryVeryVeryVeryVeryVeryVeryVeryVeryVeryLongProperty = $obj->veryVeryVeryVeryVeryVeryVeryVeryVeryVeryVeryLongProperty = 0;
 $obj->veryVeryVeryVeryVeryVeryVeryVeryVeryVeryVeryLongProperty = $obj->veryVeryVeryVeryVeryVeryVeryVeryVeryVeryVeryLongProperty = $obj->veryVeryVeryVeryVeryVeryVeryVeryVeryVeryVeryLongProperty = $veryVeryVeryVeryVeryVeryVeryVeryVeryVeryVeryLongValue;
-$obj->veryVeryVeryVeryVeryVeryVeryVeryVeryVeryVeryLongProperty->veryVeryVeryVeryVeryVeryVeryVeryVeryVeryVeryLongProperty = new MyClass()->call(
+$obj->veryVeryVeryVeryVeryVeryVeryVeryVeryVeryVeryLongProperty->veryVeryVeryVeryVeryVeryVeryVeryVeryVeryVeryLongProperty = (new MyClass())->call(
     $arg,
 );
 $obj->loooooooooooong->lookup = $this->getRequest()->getParam(
@@ -251,7 +251,7 @@ $component =
     Foo::$insertReallyReallyReallyReallyReallyReallyReallyReallyLongName;
 $component =
     $a::$insertReallyReallyReallyReallyReallyReallyReallyReallyLongName;
-$component = new Foo()
+$component = (new Foo())
     ->insertReallyReallyReallyReallyReallyReallyReallyReallyLongName;
 $component = (clone $a)
     ->insertReallyReallyReallyReallyReallyReallyReallyReallyLongName;
@@ -266,7 +266,7 @@ $component =
     Foo::$insertReallyReallyReallyReallyReallyReallyReallyReallyReallyReallyReallyReallyReallyReallyReallyLongName;
 $component =
     $a::$insertReallyReallyReallyReallyReallyReallyReallyReallyReallyReallyReallyReallyReallyReallyReallyLongName;
-$component = new Foo()
+$component = (new Foo())
     ->insertReallyReallyReallyReallyReallyReallyReallyReallyReallyReallyReallyReallyReallyReallyReallyLongName;
 $component = (clone $a)
     ->insertReallyReallyReallyReallyReallyReallyReallyReallyReallyReallyReallyReallyReallyReallyReallyLongName;
diff --git a/tests/comments/__snapshots__/jsfmt.spec.mjs.snap b/tests/comments/__snapshots__/jsfmt.spec.mjs.snap
index 5adfe5f8c..fed543709 100644
--- a/tests/comments/__snapshots__/jsfmt.spec.mjs.snap
+++ b/tests/comments/__snapshots__/jsfmt.spec.mjs.snap
@@ -6590,16 +6590,16 @@ $inspect = $condition
 
 $extractTextPluginOptions = $shouldUseRelativeAssetPaths
     ? // Making sure that the publicPath goes back to to build folder.
-    ["publicPath" => new Foo($cssFilename->split("/")->length)->join("../")]
+    ["publicPath" => (new Foo($cssFilename->split("/")->length))->join("../")]
     : [];
 
 $extractTextPluginOptions = $shouldUseRelativeAssetPaths
     ? // Making sure that the publicPath goes back to to build folder.
-    ["publicPath" => new Foo($cssFilename->split("/")->length)->join("../")]
+    ["publicPath" => (new Foo($cssFilename->split("/")->length))->join("../")]
     : [];
 
 $extractTextPluginOptions = $shouldUseRelativeAssetPaths // Making sure that the publicPath goes back to to build folder.
-    ? ["publicPath" => new Foo($cssFilename->split("/")->length)->join("../")]
+    ? ["publicPath" => (new Foo($cssFilename->split("/")->length))->join("../")]
     : [];
 
 $var =
diff --git a/tests/member_chain/__snapshots__/jsfmt.spec.mjs.snap b/tests/member_chain/__snapshots__/jsfmt.spec.mjs.snap
index 4d8631650..548a8e419 100644
--- a/tests/member_chain/__snapshots__/jsfmt.spec.mjs.snap
+++ b/tests/member_chain/__snapshots__/jsfmt.spec.mjs.snap
@@ -87,10 +87,10 @@ $superSupersuperSupersuperSupersuperSupersuperSuperLong->{$exampleOfOrderOfGette
 $superSupersuperSupersuperSupersuperSupersuperSuperLong::$exampleOfOrderOfGetterAndSetterReordered;
 $superSupersuperSupersuperSupersuperSupersuperSuperLong
     ::$exampleOfOrderOfGetterAndSetterReordered[0];
-$superSupersuperSupersuperSupersuperSupersuperSuperLong = new SuperSuperSuperSuperSuperSuperLongClassName()
+$superSupersuperSupersuperSupersuperSupersuperSuperLong = (new SuperSuperSuperSuperSuperSuperLongClassName())
     ->some_very_long_member_expression;
 new $superSupersuperSupersuperSupersuperSupersuperSuperLong->superSupersuperSupersuperSupersuperSupersuperSuperLong->superSupersuperSupersuperSupersuperSupersuperSuperLong();
-new $superSupersuperSupersuperSupersuperSupersuperSuperLong->superSupersuperSupersuperSupersuperSupersuperSuperLong->superSupersuperSupersuperSupersuperSupersuperSuperLong()
+(new $superSupersuperSupersuperSupersuperSupersuperSuperLong->superSupersuperSupersuperSupersuperSupersuperSuperLong->superSupersuperSupersuperSupersuperSupersuperSuperLong())
     ->superSupersuperSupersuperSupersuperSupersuperSuperLong;
 $test =
     $superSupersuperSupersuperSupersuperSupersuperSuperLong->exampleOfOrderOfGetterAndSetterReordered;
@@ -241,7 +241,7 @@ $object[
         : $helper->responseBody($defaultUser)
 ]->map();
 
-new TestClassWithReallyReallyReallyReallyReallyReallyReallyReallyReallyLongName()
+(new TestClassWithReallyReallyReallyReallyReallyReallyReallyReallyReallyLongName())
     ->map()
     ->filter();
 
@@ -565,14 +565,14 @@ $brian->hotel->orders()->ordered()->with("smith")->get();
 $brian::$hotel->orders()->ordered()->with("smith")->get();
 $brian["hotel"]->orders()->ordered()->with("smith")->get();
 Foo::$hotel->orders()->ordered()->with("smith")->get();
-new Foo()->hotel->orders()->ordered()->with("smith")->get();
+(new Foo())->hotel->orders()->ordered()->with("smith")->get();
 (clone $a)->hotel->orders()->ordered()->with("smith")->get();
 
 $var = $brian->hotel->orders()->ordered()->with("smith")->get();
 $var = $brian::$hotel->orders()->ordered()->with("smith")->get();
 $var = $brian["hotel"]->orders()->ordered()->with("smith")->get();
 $var = Foo::$hotel->orders()->ordered()->with("smith")->get();
-$var = new Foo()->hotel->orders()->ordered()->with("smith")->get();
+$var = (new Foo())->hotel->orders()->ordered()->with("smith")->get();
 $var = (clone $a)->hotel->orders()->ordered()->with("smith")->get();
 
 $var = Foo::keys($items)
@@ -583,10 +583,10 @@ $var = Foo::keys($items)
         return $x * 2;
     });
 
-new static(func_get_args())->push($this)->each(function ($item) {
+(new static(func_get_args()))->push($this)->each(function ($item) {
     VarDumper::dump($item);
 });
-new static(func_get_args())
+(new static(func_get_args()))
     ->offset(10)
     ->push($this)
     ->each(function ($item) {
@@ -812,8 +812,8 @@ $window
     ->first()
     ->second();
 
-new Foo()->call($foo->bar->baz)->first()->second();
-new Foo()
+(new Foo())->call($foo->bar->baz)->first()->second();
+(new Foo())
     ->call($foo->bar->baz->foo())
     ->first()
     ->second();
diff --git a/tests/new/__snapshots__/jsfmt.spec.mjs.snap b/tests/new/__snapshots__/jsfmt.spec.mjs.snap
index 177c147da..51d18a506 100644
--- a/tests/new/__snapshots__/jsfmt.spec.mjs.snap
+++ b/tests/new/__snapshots__/jsfmt.spec.mjs.snap
@@ -17,6 +17,9 @@ $bar = 'MyClassName';
 $foo = new $bar;
 $foo = new $bar();
 
+// https://github.com/prettier/plugin-php/issues/2440
+$timestamp = (new DateTimeImmutable())->format(DATE_ATOM);
+
 abstract class A
 {
     public static function create()
@@ -211,6 +214,9 @@ $bar = "MyClassName";
 $foo = new $bar();
 $foo = new $bar();
 
+// https://github.com/prettier/plugin-php/issues/2440
+$timestamp = (new DateTimeImmutable())->format(DATE_ATOM);
+
 abstract class A
 {
     public static function create()
@@ -453,6 +459,9 @@ $bar = 'MyClassName';
 $foo = new $bar;
 $foo = new $bar();
 
+// https://github.com/prettier/plugin-php/issues/2440
+$timestamp = (new DateTimeImmutable())->format(DATE_ATOM);
+
 abstract class A
 {
     public static function create()
@@ -647,6 +656,9 @@ $bar = "MyClassName";
 $foo = new $bar();
 $foo = new $bar();
 
+// https://github.com/prettier/plugin-php/issues/2440
+$timestamp = (new DateTimeImmutable())->format(DATE_ATOM);
+
 abstract class A
 {
     public static function create()
@@ -656,12 +668,12 @@ abstract class A
     }
 }
 
-$class = new Foo()->veryVeryVeryVeryVeryVeryVeryVeryVeryVeryVeryVeryVeryVeryVeryVeryVeryLongMethod();
-$class = new Foo([
+$class = (new Foo())->veryVeryVeryVeryVeryVeryVeryVeryVeryVeryVeryVeryVeryVeryVeryVeryVeryLongMethod();
+$class = (new Foo([
     "VeryVeryVeryVeryVeryVeryVeryVeryVeryLongKey" =>
         "VeryVeryVeryVeryVeryVeryVeryVeryVeryLongValue",
-])->veryVeryVeryVeryVeryVeryVeryVeryVeryVeryVeryVeryVeryVeryVeryVeryVeryLongMethod();
-$class = new PendingDispatch(new $this->class(...func_get_args()))->chain(
+]))->veryVeryVeryVeryVeryVeryVeryVeryVeryVeryVeryVeryVeryVeryVeryVeryVeryLongMethod();
+$class = (new PendingDispatch(new $this->class(...func_get_args())))->chain(
     $this->chain,
 );
 $dumper = in_array(PHP_SAPI, ["cli", "phpdbg"])
@@ -678,7 +690,7 @@ $class = new static(
 $response = new \\Illuminate\\Http\\JsonResponse(
     new JsonResponseTestJsonSerializeObject(),
 );
-$result = new Pipeline(new \\Illuminate\\Container\\Container())
+$result = (new Pipeline(new \\Illuminate\\Container\\Container()))
     ->send("foo")
     ->through([new PipelineTestPipeOne()])
     ->then(function ($piped) {
diff --git a/tests/new/new.php b/tests/new/new.php
index a4a16e1f1..efb58c000 100644
--- a/tests/new/new.php
+++ b/tests/new/new.php
@@ -8,6 +8,9 @@
 $foo = new $bar;
 $foo = new $bar();
 
+// https://github.com/prettier/plugin-php/issues/2440
+$timestamp = (new DateTimeImmutable())->format(DATE_ATOM);
+
 abstract class A
 {
     public static function create()
diff --git a/tests/parens/__snapshots__/jsfmt.spec.mjs.snap b/tests/parens/__snapshots__/jsfmt.spec.mjs.snap
index 7a00c40a9..de7727794 100644
--- a/tests/parens/__snapshots__/jsfmt.spec.mjs.snap
+++ b/tests/parens/__snapshots__/jsfmt.spec.mjs.snap
@@ -4865,11 +4865,11 @@ $var = $var[0][1]::foo();
 $var = $var[0]->foo()->baz;
 $var = $var[0]->foo()->baz;
 
-$var = new Foo()->bar;
-$var = new Foo()::bar;
-$var = new Foo()->bar();
-$var = new Foo()::bar();
-$var = new Foo()[1];
+$var = (new Foo())->bar;
+$var = (new Foo())::bar;
+$var = (new Foo())->bar();
+$var = (new Foo())::bar();
+$var = (new Foo())[1];
 
 $var = $var->bar()();
 $var = $var->bar()();
@@ -5181,46 +5181,46 @@ new Translator(
 <?php
 $var = new Foo();
 $var = new Foo();
-$var = new Foo()->c();
-new Foo()->prop;
-new Foo()->method();
-new Foo()->$var;
+$var = (new Foo())->c();
+(new Foo())->prop;
+(new Foo())->method();
+(new Foo())->$var;
 $var = new class {
     public function log($msg)
     {
         echo $msg;
     }
 };
-$var = new foo()->bar();
-$var = new foo()->bar()->foo();
-$var = new foo()->bar()->foo();
-$var = new foo()->bar()->foo();
-$var = new foo()->bar()->foo()[0];
-$var = new foo()->bar()->foo()[0][1];
-$var = new foo()->bar()->foo()->baz();
-$var = new $foo()->bar;
-$var = new $bar->y()->x;
-new SortOfLongClassName()
+$var = (new foo())->bar();
+$var = (new foo())->bar()->foo();
+$var = (new foo())->bar()->foo();
+$var = (new foo())->bar()->foo();
+$var = (new foo())->bar()->foo()[0];
+$var = (new foo())->bar()->foo()[0][1];
+$var = (new foo())->bar()->foo()->baz();
+$var = (new $foo())->bar;
+$var = (new $bar->y())->x;
+(new SortOfLongClassName())
     ->withALongMethodName()
     ->andAnother()
     ->toPushItPast80Chars();
-$asdf = new SortOfLongClassName()
+$asdf = (new SortOfLongClassName())
     ->withALongMethodName()
     ->andAnother()
     ->toPushItPast80Chars();
-$var = new foo()[0];
-$var = new foo()[0]["string"];
-$var = new Foo()::foo;
-$var = new Foo()::$foo;
+$var = (new foo())[0];
+$var = (new foo())[0]["string"];
+$var = (new Foo())::foo;
+$var = (new Foo())::$foo;
 $var = new $a->b();
 $var = new $a->b();
-$var = new $a()->b();
-$var = new $a()->b();
-new class {}->foo;
-new class {}->foo();
-new class {}();
-new class {}["foo"];
-$var = new class {}->foo;
+$var = (new $a())->b();
+$var = (new $a())->b();
+(new class {})->foo;
+(new class {})->foo();
+(new class {})();
+(new class {})["foo"];
+$var = (new class {})->foo;
 
 
 ================================================================================
diff --git a/tests/staticlookup/__snapshots__/jsfmt.spec.mjs.snap b/tests/staticlookup/__snapshots__/jsfmt.spec.mjs.snap
index 121cb5059..e2ff9cef4 100644
--- a/tests/staticlookup/__snapshots__/jsfmt.spec.mjs.snap
+++ b/tests/staticlookup/__snapshots__/jsfmt.spec.mjs.snap
@@ -1,4 +1,4 @@
-// Jest Snapshot v1, https://goo.gl/fbAQLP
+// Jest Snapshot v1, https://jestjs.io/docs/snapshot-testing
 
 exports[`single.php 1`] = `
 ====================================options=====================================
@@ -344,7 +344,7 @@ $var = $var[0]::foo;
 $var = $var[0][1]::foo;
 $var = $var[0][1]::foo;
 $var = $var[0][1]::foo;
-$var = new Foo()::bar;
+$var = (new Foo())::bar;
 $var = Foo::$bar["baz"]();
 $var = Foo::$bar["baz"]();
 $var = Foo::{$bar["baz"]}();