diff --git a/conf/config.neon b/conf/config.neon
index 977fb09f96..010e1e9e46 100644
--- a/conf/config.neon
+++ b/conf/config.neon
@@ -895,6 +895,11 @@ services:
 		tags:
 			- phpstan.broker.dynamicFunctionReturnTypeExtension
 
+	-
+		class: PHPStan\Type\Php\HashFunctionsReturnTypeExtension
+		tags:
+			- phpstan.broker.dynamicFunctionReturnTypeExtension
+
 	-
 		class: PHPStan\Type\Php\SimpleXMLElementClassPropertyReflectionExtension
 		tags:
diff --git a/resources/functionMap.php b/resources/functionMap.php
index 5fe95c7f47..f9d4b24d28 100644
--- a/resources/functionMap.php
+++ b/resources/functionMap.php
@@ -3906,7 +3906,7 @@
 'HaruPage::stroke' => ['bool', 'close_path='=>'bool'],
 'HaruPage::textOut' => ['bool', 'x'=>'float', 'y'=>'float', 'text'=>'string'],
 'HaruPage::textRect' => ['bool', 'left'=>'float', 'top'=>'float', 'right'=>'float', 'bottom'=>'float', 'text'=>'string', 'align='=>'int'],
-'hash' => ['string', 'algo'=>'string', 'data'=>'string', 'raw_output='=>'bool'],
+'hash' => ['string|false', 'algo'=>'string', 'data'=>'string', 'raw_output='=>'bool'],
 'hash_algos' => ['array'],
 'hash_copy' => ['HashContext', 'context'=>'HashContext'],
 'hash_equals' => ['bool', 'known_string'=>'string', 'user_string'=>'string'],
diff --git a/src/Type/Php/HashFunctionsReturnTypeExtension.php b/src/Type/Php/HashFunctionsReturnTypeExtension.php
new file mode 100644
index 0000000000..402bc24196
--- /dev/null
+++ b/src/Type/Php/HashFunctionsReturnTypeExtension.php
@@ -0,0 +1,46 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Type\Php;
+
+use PhpParser\Node\Expr\FuncCall;
+use PHPStan\Analyser\Scope;
+use PHPStan\Reflection\FunctionReflection;
+use PHPStan\Reflection\ParametersAcceptorSelector;
+use PHPStan\Type\Constant\ConstantBooleanType;
+use PHPStan\Type\DynamicFunctionReturnTypeExtension;
+use PHPStan\Type\MixedType;
+use PHPStan\Type\StringType;
+use PHPStan\Type\Type;
+use PHPStan\Type\TypeUtils;
+
+final class HashFunctionsReturnTypeExtension implements DynamicFunctionReturnTypeExtension
+{
+
+	public function isFunctionSupported(FunctionReflection $functionReflection): bool
+	{
+		return $functionReflection->getName() === 'hash';
+	}
+
+	public function getTypeFromFunctionCall(FunctionReflection $functionReflection, FuncCall $functionCall, Scope $scope): Type
+	{
+		$defaultReturnType = ParametersAcceptorSelector::selectSingle($functionReflection->getVariants())->getReturnType();
+
+		if (!isset($functionCall->args[0])) {
+			return $defaultReturnType;
+		}
+
+		$argType = $scope->getType($functionCall->args[0]->value);
+		if ($argType instanceof MixedType) {
+			return TypeUtils::toBenevolentUnion($defaultReturnType);
+		}
+
+		$values = TypeUtils::getConstantStrings($argType);
+		if (count($values) !== 1) {
+			return TypeUtils::toBenevolentUnion($defaultReturnType);
+		}
+		$string = $values[0];
+
+		return in_array($string->getValue(), hash_algos(), true) ? new StringType() : new ConstantBooleanType(false);
+	}
+
+}
diff --git a/tests/PHPStan/Analyser/NodeScopeResolverTest.php b/tests/PHPStan/Analyser/NodeScopeResolverTest.php
index 771ce6ee55..c3c22e8f5a 100644
--- a/tests/PHPStan/Analyser/NodeScopeResolverTest.php
+++ b/tests/PHPStan/Analyser/NodeScopeResolverTest.php
@@ -5954,6 +5954,22 @@ public function dataFunctions(): array
 				'(string|false)',
 				'$hashHmacFileVariable',
 			],
+			[
+				'string',
+				'$hash',
+			],
+			[
+				'string',
+				'$hashRaw',
+			],
+			[
+				'false',
+				'$hashRandom',
+			],
+			[
+				'string',
+				'$hashMixed',
+			],
 		];
 	}
 
diff --git a/tests/PHPStan/Analyser/data/functions.php b/tests/PHPStan/Analyser/data/functions.php
index 9af80a8edf..173a4cd5f5 100644
--- a/tests/PHPStan/Analyser/data/functions.php
+++ b/tests/PHPStan/Analyser/data/functions.php
@@ -135,4 +135,10 @@
 $hashHmacFileRandom = hash_hmac_file('random', 'data', 'key');
 $hashHmacFileVariable = hash_hmac_file($string, 'data', 'key');
 
+$hash = hash('sha256', 'data', false);
+$hashRaw = hash('sha256', 'data', true);
+$hashRandom = hash('random', 'data', false);
+/** @var mixed $mixed */
+$mixed = doFoo();
+$hashMixed = hash('md5', $mixed, false);
 die;