diff --git a/src/Analyser/MutatingScope.php b/src/Analyser/MutatingScope.php
index a15d08bac9..c987a27457 100644
--- a/src/Analyser/MutatingScope.php
+++ b/src/Analyser/MutatingScope.php
@@ -1774,7 +1774,7 @@ private function resolveType(Expr $node): Type
 						}
 					} else {
 						$arrayBuilder->degradeToGeneralArray();
-						$arrayBuilder->setOffsetValueType(new IntegerType(), $valueType->getIterableValueType());
+						$arrayBuilder->setOffsetValueType(new IntegerType(), $valueType->getIterableValueType(), !$valueType->isIterableAtLeastOnce()->yes() && !$valueType->getIterableValueType()->isIterableAtLeastOnce()->yes());
 					}
 				} else {
 					$arrayBuilder->setOffsetValueType(
diff --git a/src/Type/Constant/ConstantArrayTypeBuilder.php b/src/Type/Constant/ConstantArrayTypeBuilder.php
index aebd713e9e..04c93f3c73 100644
--- a/src/Type/Constant/ConstantArrayTypeBuilder.php
+++ b/src/Type/Constant/ConstantArrayTypeBuilder.php
@@ -105,6 +105,9 @@ public function setOffsetValueType(?Type $offsetType, Type $valueType, bool $opt
 
 		$this->keyTypes[] = TypeUtils::generalizeType($offsetType, GeneralizePrecision::moreSpecific());
 		$this->valueTypes[] = $valueType;
+		if ($optional) {
+			$this->optionalKeys[] = count($this->keyTypes) - 1;
+		}
 		$this->degradeToGeneralArray = true;
 	}
 
diff --git a/tests/PHPStan/Analyser/NodeScopeResolverTest.php b/tests/PHPStan/Analyser/NodeScopeResolverTest.php
index ffcc6d973d..68294b6ef3 100644
--- a/tests/PHPStan/Analyser/NodeScopeResolverTest.php
+++ b/tests/PHPStan/Analyser/NodeScopeResolverTest.php
@@ -533,6 +533,7 @@ public function dataFileAsserts(): iterable
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/bug-5017.php');
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/bug-5992.php');
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/bug-6001.php');
+		yield from $this->gatherAssertTypes(__DIR__ . '/data/bug-5287.php');
 
 		if (PHP_VERSION_ID >= 70400) {
 			yield from $this->gatherAssertTypes(__DIR__ . '/data/bug-5458.php');
diff --git a/tests/PHPStan/Analyser/data/bug-5287.php b/tests/PHPStan/Analyser/data/bug-5287.php
new file mode 100644
index 0000000000..3bcb5eb4fb
--- /dev/null
+++ b/tests/PHPStan/Analyser/data/bug-5287.php
@@ -0,0 +1,59 @@
+<?php declare(strict_types=1);
+
+namespace Bug5287;
+
+use function PHPStan\Testing\assertType;
+
+/**
+ * @param list<mixed> $arr
+ */
+function foo(array $arr): void
+{
+	$arrSpread = [...$arr];
+	assertType('array<int, mixed>', $arrSpread);
+}
+
+/**
+ * @param list<non-empty-array> $arr
+ */
+function foo2(array $arr): void
+{
+	$arrSpread = [...$arr];
+	assertType('non-empty-array<int, non-empty-array>', $arrSpread);
+}
+
+/**
+ * @param non-empty-list<string> $arr
+ */
+function foo3(array $arr): void
+{
+	$arrSpread = [...$arr];
+	assertType('non-empty-array<int, string>', $arrSpread);
+}
+
+/**
+ * @param non-empty-array<string, int> $arr
+ */
+function foo3(array $arr): void
+{
+	$arrSpread = [...$arr];
+	assertType('non-empty-array<int, int>', $arrSpread);
+}
+
+/**
+ * @param non-empty-array<mixed, bool|int> $arr
+ */
+function foo4(array $arr): void
+{
+	$arrSpread = [...$arr];
+	assertType('non-empty-array<int, bool|int>', $arrSpread);
+}
+
+/**
+ * @param array{foo: 17, bar: 19} $arr
+ */
+function bar(array $arr): void
+{
+	$arrSpread = [...$arr];
+	assertType('array{17, 19}', $arrSpread);
+}