diff --git a/src/Analyser/MutatingScope.php b/src/Analyser/MutatingScope.php
index a43ba35dda5..b82d5c1119b 100644
--- a/src/Analyser/MutatingScope.php
+++ b/src/Analyser/MutatingScope.php
@@ -1574,7 +1574,7 @@ public function enterPropertyHook(
 
 		$realParameterTypes = $this->getRealParameterTypes($hook);
 
-		return $this->enterFunctionLike(
+		$scope = $this->enterFunctionLike(
 			new PhpMethodFromParserNodeReflection(
 				$this->getClassReflection(),
 				$hook,
@@ -1606,6 +1606,12 @@ public function enterPropertyHook(
 			),
 			true,
 		);
+
+		if ($hookName === 'set' && !$this->getClassReflection()->getNativeProperty($propertyName)->getNativeReflection()->hasDefaultValue()) {
+			$scope = $scope->invalidateExpression(new PropertyInitializationExpr($propertyName));
+		}
+
+		return $scope;
 	}
 
 	private function transformStaticType(Type $type): Type
diff --git a/tests/PHPStan/Rules/Variables/IssetRuleTest.php b/tests/PHPStan/Rules/Variables/IssetRuleTest.php
index fd841e49b16..c2a29dd0116 100644
--- a/tests/PHPStan/Rules/Variables/IssetRuleTest.php
+++ b/tests/PHPStan/Rules/Variables/IssetRuleTest.php
@@ -526,6 +526,19 @@ public function testBug9503(): void
 		$this->analyse([__DIR__ . '/data/bug-9503.php'], []);
 	}
 
+	#[RequiresPhp('>= 8.4')]
+	public function testBug13473(): void
+	{
+		$this->treatPhpDocTypesAsCertain = true;
+
+		$this->analyse([__DIR__ . '/data/bug-13473.php'], [
+			[
+				'Property Bug13473\Bar::$bar in isset() is not nullable nor uninitialized.',
+				30,
+			],
+		]);
+	}
+
 	public function testBug14393(): void
 	{
 		$this->treatPhpDocTypesAsCertain = true;
diff --git a/tests/PHPStan/Rules/Variables/data/bug-13473.php b/tests/PHPStan/Rules/Variables/data/bug-13473.php
new file mode 100644
index 00000000000..558228d1d2b
--- /dev/null
+++ b/tests/PHPStan/Rules/Variables/data/bug-13473.php
@@ -0,0 +1,41 @@
+<?php // lint >= 8.4
+
+declare(strict_types = 1);
+
+namespace Bug13473;
+
+class Foo {
+    private(set) int $bar {
+        get => $this->bar;
+        set(int $bar) {
+            if (isset($this->bar)) {
+                throw new \Exception('bar is set');
+            }
+            $this->bar = $bar;
+        }
+    }
+
+    public function __construct(int $bar)
+    {
+        $this->bar = $bar;
+    }
+}
+
+$foo = new Foo(10);
+
+class Bar {
+    private(set) int $bar = 1 {
+        get => $this->bar;
+        set(int $bar) {
+            if (isset($this->bar)) {
+                throw new \Exception('bar is set');
+            }
+            $this->bar = $bar;
+        }
+    }
+
+    public function __construct(int $bar)
+    {
+        $this->bar = $bar;
+    }
+}