diff --git a/src/Rules/FunctionCallParametersCheck.php b/src/Rules/FunctionCallParametersCheck.php
index 130dd0bef8..d320c24d60 100644
--- a/src/Rules/FunctionCallParametersCheck.php
+++ b/src/Rules/FunctionCallParametersCheck.php
@@ -30,6 +30,7 @@
 use function array_key_exists;
 use function count;
 use function implode;
+use function in_array;
 use function is_int;
 use function is_string;
 use function max;
@@ -128,30 +129,32 @@ public function check(
 			if ($arg->unpack) {
 				$arrays = $type->getConstantArrays();
 				if (count($arrays) > 0) {
-					$minKeys = null;
+					$maxKeys = null;
 					foreach ($arrays as $array) {
 						$countType = $array->getArraySize();
 						if ($countType instanceof ConstantIntegerType) {
 							$keysCount = $countType->getValue();
 						} elseif ($countType instanceof IntegerRangeType) {
-							$keysCount = $countType->getMin();
+							$keysCount = $countType->getMax();
 							if ($keysCount === null) {
 								throw new ShouldNotHappenException();
 							}
 						} else {
 							throw new ShouldNotHappenException();
 						}
-						if ($minKeys !== null && $keysCount >= $minKeys) {
+						if ($maxKeys !== null && $keysCount >= $maxKeys) {
 							continue;
 						}
 
-						$minKeys = $keysCount;
+						$maxKeys = $keysCount;
 					}
 
-					for ($j = 0; $j < $minKeys; $j++) {
+					for ($j = 0; $j < $maxKeys; $j++) {
 						$types = [];
 						$commonKey = null;
+						$isOptionalKey = false;
 						foreach ($arrays as $constantArray) {
+							$isOptionalKey = in_array($j, $constantArray->getOptionalKeys(), true);
 							$types[] = $constantArray->getValueTypes()[$j];
 							$keyType = $constantArray->getKeyTypes()[$j];
 							if ($commonKey === null) {
@@ -165,6 +168,10 @@ public function check(
 							$keyArgumentName = $commonKey;
 							$hasNamedArguments = true;
 						}
+						if ($isOptionalKey) {
+							continue;
+						}
+
 						$arguments[] = [
 							$arg->value,
 							TypeCombinator::union(...$types),
diff --git a/tests/PHPStan/Rules/Classes/InstantiationRuleTest.php b/tests/PHPStan/Rules/Classes/InstantiationRuleTest.php
index 657c47bd75..43b9091daf 100644
--- a/tests/PHPStan/Rules/Classes/InstantiationRuleTest.php
+++ b/tests/PHPStan/Rules/Classes/InstantiationRuleTest.php
@@ -499,4 +499,9 @@ public function testBug10248(): void
 		$this->analyse([__DIR__ . '/data/bug-10248.php'], []);
 	}
 
+	public function testBug11815(): void
+	{
+		$this->analyse([__DIR__ . '/data/bug-11815.php'], []);
+	}
+
 }
diff --git a/tests/PHPStan/Rules/Classes/data/bug-11815.php b/tests/PHPStan/Rules/Classes/data/bug-11815.php
new file mode 100644
index 0000000000..c08dccb9ea
--- /dev/null
+++ b/tests/PHPStan/Rules/Classes/data/bug-11815.php
@@ -0,0 +1,43 @@
+<?php // lint >= 8.2
+
+declare(strict_types = 1);
+
+class Dimensions
+{
+    public function __construct(
+        public int $width,
+        public int $height,
+    ) {
+    }
+}
+
+class StoreProcessorResult
+{
+    public function __construct(
+        public string $path,
+        public string $mimetype,
+        public Dimensions $dimensions,
+        public int $filesize,
+        public true|null $identical = null,
+     ) {
+     }
+}
+
+/**
+ * @return array{path: string, identical?: true}
+ */
+function getPath(): array
+{
+	$data = ['path' => 'some/path'];
+	if ((bool)rand(0, 1)) {
+		$data['identical'] = true;
+	}
+	return $data;
+}
+
+$data = getPath();
+$data['dimensions'] = new Dimensions(100, 100);
+$data['mimetype'] = 'image/png';
+$data['filesize'] = 123456;
+
+$dto = new StoreProcessorResult(...$data);