diff --git a/phpstan-baseline.neon b/phpstan-baseline.neon
index d91eb9b78bf..a7df6cbabe5 100644
--- a/phpstan-baseline.neon
+++ b/phpstan-baseline.neon
@@ -1776,7 +1776,7 @@ parameters:
 		-
 			rawMessage: 'Doing instanceof PHPStan\Type\IterableType is error-prone and deprecated. Use Type::isIterable() instead.'
 			identifier: phpstanApi.instanceofType
-			count: 1
+			count: 3
 			path: src/Type/UnionType.php
 
 		-
diff --git a/src/Type/UnionType.php b/src/Type/UnionType.php
index 208e5e3b43a..6fee6d9fdac 100644
--- a/src/Type/UnionType.php
+++ b/src/Type/UnionType.php
@@ -25,6 +25,7 @@
 use PHPStan\TrinaryLogic;
 use PHPStan\Type\Enum\EnumCaseObjectType;
 use PHPStan\Type\Generic\GenericClassStringType;
+use PHPStan\Type\Generic\GenericObjectType;
 use PHPStan\Type\Generic\TemplateIterableType;
 use PHPStan\Type\Generic\TemplateMixedType;
 use PHPStan\Type\Generic\TemplateType;
@@ -33,6 +34,7 @@
 use PHPStan\Type\Generic\TemplateUnionType;
 use PHPStan\Type\Traits\NonGeneralizableTypeTrait;
 use Throwable;
+use Traversable;
 use function array_diff_assoc;
 use function array_fill_keys;
 use function array_map;
@@ -194,6 +196,16 @@ public function getConstantStrings(): array
 
 	public function accepts(Type $type, bool $strictTypes): AcceptsResult
 	{
+		if ($type instanceof IterableType && !$type instanceof TemplateIterableType) {
+			return $this->accepts(new UnionType([
+				new ArrayType($type->getIterableKeyType(), $type->getIterableValueType()),
+				new GenericObjectType(Traversable::class, [
+					$type->getIterableKeyType(),
+					$type->getIterableValueType(),
+				]),
+			]), $strictTypes);
+		}
+
 		foreach (self::EQUAL_UNION_CLASSES as $baseClass => $classes) {
 			if (!$type->equals(new ObjectType($baseClass))) {
 				continue;
@@ -1073,6 +1085,16 @@ public function toCoercedArgumentType(bool $strictTypes): Type
 
 	public function inferTemplateTypes(Type $receivedType): TemplateTypeMap
 	{
+		if ($receivedType instanceof IterableType && !$receivedType instanceof TemplateIterableType) {
+			$receivedType = new UnionType([
+				new ArrayType($receivedType->getIterableKeyType(), $receivedType->getIterableValueType()),
+				new GenericObjectType(Traversable::class, [
+					$receivedType->getIterableKeyType(),
+					$receivedType->getIterableValueType(),
+				]),
+			]);
+		}
+
 		$types = TemplateTypeMap::createEmpty();
 		if ($receivedType instanceof UnionType) {
 			$myTypes = [];
diff --git a/tests/PHPStan/Rules/Functions/CallToFunctionParametersRuleTest.php b/tests/PHPStan/Rules/Functions/CallToFunctionParametersRuleTest.php
index 77ef9843bfe..ba544ae9d35 100644
--- a/tests/PHPStan/Rules/Functions/CallToFunctionParametersRuleTest.php
+++ b/tests/PHPStan/Rules/Functions/CallToFunctionParametersRuleTest.php
@@ -2735,4 +2735,9 @@ public function testBug10559(): void
 		$this->analyse([__DIR__ . '/data/bug-10559.php'], []);
 	}
 
+	public function testBug13247(): void
+	{
+		$this->analyse([__DIR__ . '/data/bug-13247.php'], []);
+	}
+
 }
diff --git a/tests/PHPStan/Rules/Functions/data/bug-13247.php b/tests/PHPStan/Rules/Functions/data/bug-13247.php
new file mode 100644
index 00000000000..5acd49e8793
--- /dev/null
+++ b/tests/PHPStan/Rules/Functions/data/bug-13247.php
@@ -0,0 +1,35 @@
+<?php // lint >= 8.0
+
+declare(strict_types = 1);
+
+namespace Bug13247;
+
+use Traversable;
+
+/**
+ * @template K as array-key
+ * @template V
+ *
+ * @param array<K, V>|Traversable<K, V> $input
+ *
+ * @return array<K, V>
+ */
+function as_array(array|Traversable $input): array {
+    if ($input instanceof Traversable) {
+        return iterator_to_array($input);
+    }
+
+    return $input;
+}
+
+/**
+ * @template K as array-key
+ * @template V
+ *
+ * @param iterable<K, V> $input
+ *
+ * @return array<K, V>
+ */
+function iter_as_array(iterable $input): array {
+    return as_array($input);
+}