diff --git a/src/Type/Php/JsonThrowOnErrorDynamicReturnTypeExtension.php b/src/Type/Php/JsonThrowOnErrorDynamicReturnTypeExtension.php
index 1b177d99f1d..aa864a3eac3 100644
--- a/src/Type/Php/JsonThrowOnErrorDynamicReturnTypeExtension.php
+++ b/src/Type/Php/JsonThrowOnErrorDynamicReturnTypeExtension.php
@@ -12,21 +12,15 @@
 use PHPStan\Reflection\FunctionReflection;
 use PHPStan\Reflection\ParametersAcceptorSelector;
 use PHPStan\Reflection\ReflectionProvider;
-use PHPStan\Type\ArrayType;
-use PHPStan\Type\BooleanType;
 use PHPStan\Type\Constant\ConstantBooleanType;
 use PHPStan\Type\Constant\ConstantIntegerType;
 use PHPStan\Type\Constant\ConstantStringType;
 use PHPStan\Type\ConstantTypeHelper;
 use PHPStan\Type\DynamicFunctionReturnTypeExtension;
-use PHPStan\Type\FloatType;
-use PHPStan\Type\IntegerType;
 use PHPStan\Type\MixedType;
 use PHPStan\Type\ObjectType;
-use PHPStan\Type\StringType;
 use PHPStan\Type\Type;
 use PHPStan\Type\TypeCombinator;
-use PHPStan\Type\UnionType;
 use stdClass;
 use function json_decode;
 
@@ -66,11 +60,7 @@ public function getTypeFromFunctionCall(
 
 		// narrow type for json_decode()
 		if ($functionReflection->getName() === 'json_decode') {
-			$jsonDecodeNarrowedType = $this->narrowTypeForJsonDecode($functionCall, $scope);
-			// improve type
-			if (! $jsonDecodeNarrowedType instanceof MixedType) {
-				$defaultReturnType = $jsonDecodeNarrowedType;
-			}
+			$defaultReturnType = $this->narrowTypeForJsonDecode($functionCall, $scope);
 		}
 
 		if (!isset($functionCall->getArgs()[$argumentPosition])) {
@@ -128,35 +118,15 @@ private function narrowTypeForJsonDecode(FuncCall $funcCall, Scope $scope): Type
 		$firstValueType = $scope->getType($firstArgValue);
 
 		if ($firstValueType instanceof ConstantStringType) {
-			$resolvedType = $this->resolveConstantStringType($firstValueType, $isForceArray);
-		} else {
-			$resolvedType = new MixedType();
-		}
-
-		// prefer specific type
-		if (! $resolvedType instanceof MixedType) {
-			return $resolvedType;
+			return $this->resolveConstantStringType($firstValueType, $isForceArray);
 		}
 
 		// fallback type
 		if ($isForceArray) {
-			return new UnionType([
-				new ArrayType(new MixedType(), new MixedType()),
-				new StringType(),
-				new FloatType(),
-				new IntegerType(),
-				new BooleanType(),
-			]);
+			return new MixedType(true, new ObjectType(stdClass::class));
 		}
 
-		// scalar types with stdClass
-		return new UnionType([
-			new ObjectType(stdClass::class),
-			new StringType(),
-			new FloatType(),
-			new IntegerType(),
-			new BooleanType(),
-		]);
+		return new MixedType(true);
 	}
 
 	/**
@@ -167,18 +137,16 @@ private function isForceArray(FuncCall $funcCall): bool
 	{
 		$args = $funcCall->getArgs();
 
-		if (!isset($args[1])) {
+		if (! isset($args[1])) {
 			return false;
 		}
 
 		$secondArgValue = $args[1]->value;
-		if ($secondArgValue instanceof ConstFetch) {
-			if ($secondArgValue->name->toLowerString() === 'true') {
-				return true;
-			}
+		if (! $secondArgValue instanceof ConstFetch) {
+			return false;
 		}
 
-		return false;
+		return $secondArgValue->name->toLowerString() === 'true';
 	}
 
 	private function resolveConstantStringType(ConstantStringType $constantStringType, bool $isForceArray): Type
diff --git a/tests/PHPStan/Analyser/LegacyNodeScopeResolverTest.php b/tests/PHPStan/Analyser/LegacyNodeScopeResolverTest.php
index d934bc9ce62..92bdde96ae0 100644
--- a/tests/PHPStan/Analyser/LegacyNodeScopeResolverTest.php
+++ b/tests/PHPStan/Analyser/LegacyNodeScopeResolverTest.php
@@ -8749,15 +8749,15 @@ public function dataPhp73Functions(): array
 				'json_encode($mixed,  $integer | JSON_THROW_ON_ERROR | JSON_NUMERIC_CHECK)',
 			],
 			[
-				'bool|float|int|stdClass|string',
+				'mixed',
 				'json_decode($mixed)',
 			],
 			[
-				'float|int|stdClass|string|true',
+				'mixed~false',
 				'json_decode($mixed, false, 512, JSON_THROW_ON_ERROR | JSON_NUMERIC_CHECK)',
 			],
 			[
-				'float|int|stdClass|string|true',
+				'mixed~false',
 				'json_decode($mixed, false, 512, $integer | JSON_THROW_ON_ERROR | JSON_NUMERIC_CHECK)',
 			],
 			[
diff --git a/tests/PHPStan/Analyser/data/json-decode/narrow_type.php b/tests/PHPStan/Analyser/data/json-decode/narrow_type.php
index 15251b69a05..e7c72b4e317 100644
--- a/tests/PHPStan/Analyser/data/json-decode/narrow_type.php
+++ b/tests/PHPStan/Analyser/data/json-decode/narrow_type.php
@@ -21,3 +21,9 @@
 
 $value = json_decode('[1, 2, 3]');
 assertType('array{1, 2, 3}', $value);
+
+
+function ($mixed) {
+	$value = json_decode($mixed);
+	assertType('mixed', $value);
+};
diff --git a/tests/PHPStan/Analyser/data/json-decode/narrow_type_with_force_array.php b/tests/PHPStan/Analyser/data/json-decode/narrow_type_with_force_array.php
index 9aefff0540f..479085c8147 100644
--- a/tests/PHPStan/Analyser/data/json-decode/narrow_type_with_force_array.php
+++ b/tests/PHPStan/Analyser/data/json-decode/narrow_type_with_force_array.php
@@ -21,3 +21,8 @@
 
 $value = json_decode('[1, 2, 3]', true);
 assertType('array{1, 2, 3}', $value);
+
+function ($mixed) {
+	$value = json_decode($mixed, true);
+	assertType('mixed~stdClass', $value);
+};