diff --git a/src/Analyser/ConstantResolver.php b/src/Analyser/ConstantResolver.php
index d7e8001de6..6d712a165b 100644
--- a/src/Analyser/ConstantResolver.php
+++ b/src/Analyser/ConstantResolver.php
@@ -159,6 +159,13 @@ public function resolvePredefinedConstant(string $resolvedConstantName): ?Type
 
 			return $this->createInteger($minVersion, $maxVersion);
 		}
+		// added in PHP 8.5
+		if ($resolvedConstantName === 'PHP_BUILD_DATE') {
+			return new IntersectionType([
+				new StringType(),
+				new AccessoryNonFalsyStringType(),
+			]);
+		}
 		if ($resolvedConstantName === 'PHP_ZTS') {
 			return new UnionType([
 				new ConstantIntegerType(0),
diff --git a/tests/PHPStan/Analyser/nsrt/predefined-constants-php85.php b/tests/PHPStan/Analyser/nsrt/predefined-constants-php85.php
new file mode 100644
index 0000000000..94e4bb53ce
--- /dev/null
+++ b/tests/PHPStan/Analyser/nsrt/predefined-constants-php85.php
@@ -0,0 +1,5 @@
+<?php
+
+use function PHPStan\Testing\assertType;
+
+assertType('non-falsy-string', PHP_BUILD_DATE);