diff --git a/src/SourceLocator/SourceStubber/PhpStormStubs/CachingVisitor.php b/src/SourceLocator/SourceStubber/PhpStormStubs/CachingVisitor.php
index 4cbe3b094..ef9a2d8a2 100644
--- a/src/SourceLocator/SourceStubber/PhpStormStubs/CachingVisitor.php
+++ b/src/SourceLocator/SourceStubber/PhpStormStubs/CachingVisitor.php
@@ -13,8 +13,11 @@
 
 use function array_key_exists;
 use function assert;
+use function class_exists;
 use function constant;
+use function count;
 use function defined;
+use function explode;
 use function in_array;
 use function is_resource;
 use function sprintf;
@@ -195,6 +198,16 @@ public function clearNodes(): void
      */
     private function updateConstantValue(Node\Expr\FuncCall|Node\Const_ $node, string $constantName): void
     {
+        // prevent autoloading while discovering class constants
+        $parts = explode('::', $constantName, 2);
+        if (count($parts) === 2) {
+            [$className, $classConstName] = $parts;
+
+            if (! class_exists($className, false)) {
+                return;
+            }
+        }
+
         if (! defined($constantName)) {
             return;
         }
diff --git a/test/unit/SourceLocator/SourceStubber/PhpStormStubsSourceStubberTest.php b/test/unit/SourceLocator/SourceStubber/PhpStormStubsSourceStubberTest.php
index 68498b083..37ae5fb39 100644
--- a/test/unit/SourceLocator/SourceStubber/PhpStormStubsSourceStubberTest.php
+++ b/test/unit/SourceLocator/SourceStubber/PhpStormStubsSourceStubberTest.php
@@ -62,6 +62,7 @@
 use function get_defined_functions;
 use function in_array;
 use function sort;
+use function spl_autoload_register;
 use function sprintf;
 
 use const PHP_VERSION_ID;
@@ -626,6 +627,19 @@ public function testCaseSensitiveConstantSearchOptimization(): void
         self::assertNull($this->sourceStubber->generateConstantStub('date_atom'));
     }
 
+    #[RunInSeparateProcess]
+    public function testUpdateConstantValueDoesNotTriggerAutoload(): void
+    {
+        spl_autoload_register(static function (string $className): void {
+            self::fail('Parsing php-src constant should not trigger userland autoloading');
+        });
+
+        $sourceStubber     = new PhpStormStubsSourceStubber(BetterReflectionSingleton::instance()->phpParser());
+        $constConstantStub = $sourceStubber->generateConstantStub('JSON_PRETTY_PRINT');
+        self::assertNotNull($constConstantStub);
+        self::assertStringContainsString("define('JSON_PRETTY_PRINT',", $constConstantStub->getStub());
+    }
+
     #[RunInSeparateProcess]
     public function testUpdateConstantValue(): void
     {