diff --git a/src/Analyser/MutatingScope.php b/src/Analyser/MutatingScope.php
index de3c4179b22..ec059692165 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(),
 				$hook,
@@ -1606,6 +1606,18 @@ public function enterPropertyHook(
 			),
 			true,
 		);
+
+		if ($hookName === 'set') {
+			$classReflection = $this->getClassReflection();
+			if (
+				!$classReflection->hasNativeProperty($propertyName)
+				|| !$classReflection->getNativeProperty($propertyName)->getNativeReflection()->hasDefaultValue()
+			) {
+				$scope->exitPropertyInitialization($propertyName);
+			}
+		}
+
+		return $scope;
 	}
 
 	private function transformStaticType(Type $type): Type
@@ -2832,6 +2844,15 @@ public function assignInitializedProperty(Type $fetchedOnType, string $propertyN
 		return $this->assignExpression(new PropertyInitializationExpr($propertyName), new MixedType(), new MixedType());
 	}
 
+	public function exitPropertyInitialization(string $propertyName): self
+	{
+		$initExprKey = $this->getNodeKey(new PropertyInitializationExpr($propertyName));
+		unset($this->expressionTypes[$initExprKey]);
+		unset($this->nativeExpressionTypes[$initExprKey]);
+
+		return $this;
+	}
+
 	public function invalidateExpression(Expr $expressionToInvalidate, bool $requireMoreCharacters = false, ?ClassReflection $invalidatingClass = null): self
 	{
 		$expressionTypes = $this->expressionTypes;
diff --git a/src/Analyser/NodeScopeResolver.php b/src/Analyser/NodeScopeResolver.php
index f616b644ab3..25d46bdeaa2 100644
--- a/src/Analyser/NodeScopeResolver.php
+++ b/src/Analyser/NodeScopeResolver.php
@@ -712,6 +712,27 @@ public function processStmtNode(
 
 			$classReflection = $scope->getClassReflection();
 
+			if (!$isConstructor && !$stmt->isStatic()) {
+				$stackName = sprintf('%s::%s', $classReflection->getName(), $stmt->name->toString());
+				$calledMethodScope = $this->calledMethodResults[$stackName] ?? null;
+				if ($calledMethodScope !== null) {
+					foreach ($calledMethodScope->expressionTypes as $typeHolder) {
+						$expr = $typeHolder->getExpr();
+						if (!$expr instanceof PropertyInitializationExpr) {
+							continue;
+						}
+						$propertyName = $expr->getPropertyName();
+						if (
+							$classReflection->hasNativeProperty($propertyName)
+							&& $classReflection->getNativeProperty($propertyName)->getNativeReflection()->hasDefaultValue()
+						) {
+							continue;
+						}
+						$methodScope = $methodScope->exitPropertyInitialization($propertyName);
+					}
+				}
+			}
+
 			if ($isConstructor) {
 				foreach ($stmt->params as $param) {
 					if ($param->flags === 0 && $param->hooks === []) {
diff --git a/tests/PHPStan/Rules/Variables/IssetRuleTest.php b/tests/PHPStan/Rules/Variables/IssetRuleTest.php
index fd841e49b16..38aafa7016b 100644
--- a/tests/PHPStan/Rules/Variables/IssetRuleTest.php
+++ b/tests/PHPStan/Rules/Variables/IssetRuleTest.php
@@ -562,4 +562,29 @@ public function testBug14393(): void
 		]);
 	}
 
+	#[RequiresPhp('>= 8.4')]
+	public function testBug13473(): void
+	{
+		$this->treatPhpDocTypesAsCertain = true;
+
+		$this->analyse([__DIR__ . '/data/bug-13473.php'], [
+			[
+				'Property Bug13473\FooWithDefault::$bar in isset() is not nullable nor uninitialized.',
+				28,
+			],
+		]);
+	}
+
+	public function testBug13473Method(): void
+	{
+		$this->treatPhpDocTypesAsCertain = true;
+
+		$this->analyse([__DIR__ . '/data/bug-13473-method.php'], [
+			[
+				'Property Bug13473Method\FooWithDefault::$bar in isset() is not nullable nor uninitialized.',
+				34,
+			],
+		]);
+	}
+
 }
diff --git a/tests/PHPStan/Rules/Variables/data/bug-13473-method.php b/tests/PHPStan/Rules/Variables/data/bug-13473-method.php
new file mode 100644
index 00000000000..893fc71a966
--- /dev/null
+++ b/tests/PHPStan/Rules/Variables/data/bug-13473-method.php
@@ -0,0 +1,39 @@
+<?php
+
+declare(strict_types = 1);
+
+namespace Bug13473Method;
+
+class Foo {
+    private int $bar;
+
+    public function __construct(int $bar)
+    {
+        $this->setBar($bar);
+    }
+
+	public function setBar(int $bar): void
+	{
+		if (isset($this->bar)) {
+			throw new \Exception('bar is set');
+		}
+		$this->bar = $bar;
+	}
+}
+
+class FooWithDefault {
+    private int $bar = 1;
+
+    public function __construct(int $bar)
+    {
+        $this->setBar($bar);
+    }
+
+	public function setBar(int $bar): void
+	{
+		if (isset($this->bar)) {
+			throw new \Exception('bar is set');
+		}
+		$this->bar = $bar;
+	}
+}
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..cdafdff10fe
--- /dev/null
+++ b/tests/PHPStan/Rules/Variables/data/bug-13473.php
@@ -0,0 +1,39 @@
+<?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;
+	}
+}
+
+class FooWithDefault {
+	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;
+	}
+}