diff --git a/src/Analyser/NodeScopeResolver.php b/src/Analyser/NodeScopeResolver.php
index d5f62a9b8a..d731e40380 100644
--- a/src/Analyser/NodeScopeResolver.php
+++ b/src/Analyser/NodeScopeResolver.php
@@ -5940,6 +5940,7 @@ private function processArgs(
 						) {
 							$this->callNodeCallback($nodeCallback, new InvalidateExprNode($arg->value), $scope, $storage);
 							$scope = $scope->invalidateExpression($arg->value, true);
+							$scope = $this->widenUniversalObjectCrateProperties($scope, $arg->value);
 						}
 					} elseif (!(new ResourceType())->isSuperTypeOf($argType)->no()) {
 						$this->callNodeCallback($nodeCallback, new InvalidateExprNode($arg->value), $scope, $storage);
@@ -5953,6 +5954,22 @@ private function processArgs(
 		return new ExpressionResult($scope, $hasYield, $isAlwaysTerminating, $throwPoints, $impurePoints);
 	}
 
+	private function widenUniversalObjectCrateProperties(MutatingScope $scope, Expr $expr): MutatingScope
+	{
+		$argType = $scope->getType($expr);
+		$stdClassType = new ObjectType('stdClass');
+
+		if (!in_array('stdClass', $argType->getObjectClassNames(), true)) {
+			return $scope;
+		}
+
+		if ($stdClassType->isSuperTypeOf($argType)->yes() && !$argType->equals($stdClassType)) {
+			return $scope->assignExpression($expr, $stdClassType, $stdClassType);
+		}
+
+		return $scope;
+	}
+
 	/**
 	 * @param MethodReflection|FunctionReflection|null $calleeReflection
 	 */
diff --git a/tests/PHPStan/Analyser/nsrt/bug-9181.php b/tests/PHPStan/Analyser/nsrt/bug-9181.php
new file mode 100644
index 0000000000..0b53a12628
--- /dev/null
+++ b/tests/PHPStan/Analyser/nsrt/bug-9181.php
@@ -0,0 +1,27 @@
+<?php declare(strict_types = 1);
+
+namespace Bug9181;
+
+use function PHPStan\Testing\assertType;
+
+class HelloWorld
+{
+	private function possiblyModifyObject(object $data): void {}
+
+	public function sayHello(): void
+	{
+		$data = (object)[
+			'search' => null,
+		];
+
+		assertType('null', $data->search);
+
+		$this->possiblyModifyObject($data);
+
+		assertType('mixed', $data->search);
+
+		if (($search = $data->search) !== null) {
+			assertType('mixed~null', $search);
+		}
+	}
+}