diff --git a/src/Type/Php/ArrayFilterFunctionReturnTypeReturnTypeExtension.php b/src/Type/Php/ArrayFilterFunctionReturnTypeReturnTypeExtension.php
index d6f5a8251c..c44d17a250 100644
--- a/src/Type/Php/ArrayFilterFunctionReturnTypeReturnTypeExtension.php
+++ b/src/Type/Php/ArrayFilterFunctionReturnTypeReturnTypeExtension.php
@@ -33,6 +33,7 @@
 use PHPStan\Type\TypeUtils;
 use function array_map;
 use function count;
+use function in_array;
 use function is_string;
 use function strtolower;
 use function substr;
@@ -192,9 +193,11 @@ private function filterByTruthyValue(Scope $scope, Error|Variable|null $itemVar,
 			$results = [];
 			foreach ($constantArrays as $constantArray) {
 				$builder = ConstantArrayTypeBuilder::createEmpty();
+				$optionalKeys = $constantArray->getOptionalKeys();
 				foreach ($constantArray->getKeyTypes() as $i => $keyType) {
 					$itemType = $constantArray->getValueTypes()[$i];
 					[$newKeyType, $newItemType, $optional] = $this->processKeyAndItemType($scope, $keyType, $itemType, $itemVar, $keyVar, $expr);
+					$optional = $optional || in_array($i, $optionalKeys, true);
 					if ($newKeyType instanceof NeverType || $newItemType instanceof NeverType) {
 						continue;
 					}
diff --git a/tests/PHPStan/Analyser/nsrt/bug-11570.php b/tests/PHPStan/Analyser/nsrt/bug-11570.php
new file mode 100644
index 0000000000..7a97062078
--- /dev/null
+++ b/tests/PHPStan/Analyser/nsrt/bug-11570.php
@@ -0,0 +1,14 @@
+<?php
+
+namespace Bug11570;
+
+use function PHPStan\Testing\assertType;
+
+/**
+ * @param array{one?: string, two?: string|null, three: string|null} $data
+ */
+function test(array $data): void
+{
+	$data = array_filter($data, fn($var) => $var !== null);
+	assertType("array{one?: string, two?: string, three?: string}", $data);
+}