diff --git a/src/Type/Php/InArrayFunctionTypeSpecifyingExtension.php b/src/Type/Php/InArrayFunctionTypeSpecifyingExtension.php
index 434373b8e3..b6bf21c49f 100644
--- a/src/Type/Php/InArrayFunctionTypeSpecifyingExtension.php
+++ b/src/Type/Php/InArrayFunctionTypeSpecifyingExtension.php
@@ -38,11 +38,16 @@ public function isFunctionSupported(FunctionReflection $functionReflection, Func
 	public function specifyTypes(FunctionReflection $functionReflection, FuncCall $node, Scope $scope, TypeSpecifierContext $context): SpecifiedTypes
 	{
 		$isStrictComparison = false;
-		if (count($node->getArgs()) >= 3) {
+		$argsCount = count($node->getArgs());
+		if ($argsCount >= 3) {
 			$strictNodeType = $scope->getType($node->getArgs()[2]->value);
 			$isStrictComparison = (new ConstantBooleanType(true))->isSuperTypeOf($strictNodeType)->yes();
 		}
 
+		if ($argsCount < 2) {
+			return new SpecifiedTypes();
+		}
+
 		$needleType = $scope->getType($node->getArgs()[0]->value);
 		$arrayType = $scope->getType($node->getArgs()[1]->value);
 		$arrayValueType = $arrayType->getIterableValueType();
diff --git a/tests/PHPStan/Analyser/AnalyserIntegrationTest.php b/tests/PHPStan/Analyser/AnalyserIntegrationTest.php
index d4da5e3e9f..53e7ae85ba 100644
--- a/tests/PHPStan/Analyser/AnalyserIntegrationTest.php
+++ b/tests/PHPStan/Analyser/AnalyserIntegrationTest.php
@@ -347,6 +347,13 @@ public function testBug1843(): void
 		$this->assertNoErrors($errors);
 	}
 
+	public function testBug9711(): void
+	{
+		$errors = $this->runAnalyse(__DIR__ . '/data/bug-9711.php');
+		$this->assertCount(1, $errors);
+		$this->assertSame('Function in_array invoked with 1 parameter, 2-3 required.', $errors[0]->getMessage());
+	}
+
 	public function testBug4713(): void
 	{
 		$errors = $this->runAnalyse(__DIR__ . '/data/bug-4713.php');
diff --git a/tests/PHPStan/Analyser/data/bug-9711.php b/tests/PHPStan/Analyser/data/bug-9711.php
new file mode 100644
index 0000000000..b7802d0196
--- /dev/null
+++ b/tests/PHPStan/Analyser/data/bug-9711.php
@@ -0,0 +1,5 @@
+<?php
+
+namespace Bug9711;
+
+echo in_array(new \stdClass());