diff --git a/README.md b/README.md
index 102f6af..454489a 100644
--- a/README.md
+++ b/README.md
@@ -45,3 +45,26 @@ The `stubs/wordpress-override.php` file provides corrected type definitions for
   stubFiles:
     - vendor/wpsyntex/polylang-phpstan/stubs/wordpress-override.php
 ```
+
+## Language switcher typing (Polylang 3.9+)
+
+Polylang 3.9 replaced `PLL_Switcher::the_languages()` with `pll_the_languages()` and the internal `WP_Syntex\Polylang\Switcher\Switcher` class.
+
+This extension provides dynamic return types for `pll_the_languages()`:
+
+| `$args` | Return type |
+|---|---|
+| `raw => true` | `array<string, mixed>` |
+| `echo => false` | `string` |
+| default (`echo => true`) | `void` |
+
+Direct usage of `WP_Syntex\Polylang\Switcher\Switcher` is typed from Polylang stubs or from Polylang source when you analyze the plugin itself.
+
+### Deprecated `PLL_Switcher`
+
+`PLL_Switcher` was removed in Polylang 3.9. When this extension is enabled, PHPStan reports:
+
+- `polylang.deprecatedSwitcher` on `new PLL_Switcher()`
+- `polylang.deprecatedSwitcherMethod` on `PLL_Switcher::the_languages()`
+
+Migrate to `pll_the_languages()` or to `WP_Syntex\Polylang\Switcher\Switcher`.
diff --git a/composer.json b/composer.json
index 4de0ef7..4ab4794 100644
--- a/composer.json
+++ b/composer.json
@@ -6,9 +6,11 @@
 	"type": "library",
 	"require": {
 		"php": "^8.0",
+		"phpstan/phpstan": "^2.0",
 		"szepeviktor/phpstan-wordpress": "^2.0"
 	},
 	"require-dev": {
+		"phpstan/phpstan-strict-rules": "^2.0",
 		"phpunit/phpunit": "^9",
 		"wpsyntex/polylang-stubs": "dev-master"
 	},
@@ -18,6 +20,7 @@
 		}
 	},
 	"scripts": {
-		"test":"vendor/bin/phpunit -d memory_limit=1G"
+		"test": "vendor/bin/phpunit -d memory_limit=1G",
+		"stan": "vendor/bin/phpstan analyse src/GuessTypeFromSwitcherArgs.php src/TheLanguagesFunctionReturnTypeExtension.php --memory-limit=512M"
 	}
 }
diff --git a/extension.neon b/extension.neon
index 76f4fcc..09c70c7 100644
--- a/extension.neon
+++ b/extension.neon
@@ -3,10 +3,6 @@ services:
 		class: WPSyntex\Polylang\PHPStan\LanguageReturnTypeExtension
 		tags:
 			- phpstan.broker.dynamicFunctionReturnTypeExtension
-	-
-		class: WPSyntex\Polylang\PHPStan\SwitcherClassReturnTypeExtension
-		tags:
-			- phpstan.broker.dynamicMethodReturnTypeExtension
 	-
 		class: WPSyntex\Polylang\PHPStan\TheLanguagesFunctionReturnTypeExtension
 		tags:
@@ -23,6 +19,10 @@ services:
 		class: WPSyntex\Polylang\PHPStan\OptionsGetDynamicMethodReturnTypeExtension
 		tags:
 			- phpstan.broker.dynamicMethodReturnTypeExtension
+	-
+		class: WPSyntex\Polylang\PHPStan\Rules\DeprecatedPllSwitcherRule
+		tags:
+			- phpstan.rules.rule
 includes:
 	- ../../szepeviktor/phpstan-wordpress/extension.neon
 parameters:
@@ -30,6 +30,8 @@ parameters:
 		- bootstrap.php
 	stubFiles:
 		- %rootDir%/../../php-stubs/wordpress-stubs/wordpress-stubs.php
+	scanFiles:
+		- stubs/pll-switcher-deprecated.php
 	dynamicConstantNames:
 		- POLYLANG_VERSION
 		- PLL_ADMIN
diff --git a/phpstan.neon.dist b/phpstan.neon.dist
new file mode 100644
index 0000000..a11b80b
--- /dev/null
+++ b/phpstan.neon.dist
@@ -0,0 +1,4 @@
+parameters:
+	level: 9
+	paths:
+		- src/
diff --git a/src/GuessTypeFromSwitcherArgs.php b/src/GuessTypeFromSwitcherArgs.php
new file mode 100644
index 0000000..1668755
--- /dev/null
+++ b/src/GuessTypeFromSwitcherArgs.php
@@ -0,0 +1,127 @@
+<?php
+
+namespace WPSyntex\Polylang\PHPStan;
+
+use PhpParser\Node\Arg;
+use PHPStan\Analyser\Scope;
+use PHPStan\TrinaryLogic;
+use PHPStan\Type\ArrayType;
+use PHPStan\Type\Constant\ConstantArrayType;
+use PHPStan\Type\Constant\ConstantStringType;
+use PHPStan\Type\MixedType;
+use PHPStan\Type\StringType;
+use PHPStan\Type\Type;
+use PHPStan\Type\TypeCombinator;
+use PHPStan\Type\VoidType;
+
+/**
+ * Infers pll_the_languages() return types from switcher arguments.
+ *
+ * Mirrors the runtime branches in polylang/src/api.php:
+ * raw truthy → array, echo false → string, otherwise → void.
+ */
+trait GuessTypeFromSwitcherArgs {
+	private function guessPllTheLanguagesReturnType( Arg $arg, Scope $scope ): Type {
+		$isRaw = $this->guessBooleanArg( $arg, $scope, 'raw', TrinaryLogic::createNo() );
+
+		if ( $isRaw->yes() ) {
+			return $this->getRawReturnType();
+		}
+
+		if ( $isRaw->maybe() ) {
+			return TypeCombinator::union(
+				$this->getRawReturnType(),
+				$this->guessNonRawReturnType( $arg, $scope )
+			);
+		}
+
+		return $this->guessNonRawReturnType( $arg, $scope );
+	}
+
+	private function guessNonRawReturnType( Arg $arg, Scope $scope ): Type {
+		// `echo` defaults to true: the markup is printed and nothing is returned.
+		$isEcho = $this->guessBooleanArg( $arg, $scope, 'echo', TrinaryLogic::createYes() );
+
+		if ( $isEcho->yes() ) {
+			return new VoidType();
+		}
+
+		if ( $isEcho->no() ) {
+			return new StringType();
+		}
+
+		return TypeCombinator::union( new VoidType(), new StringType() );
+	}
+
+	private function getRawReturnType(): Type {
+		return new ArrayType( new StringType(), new MixedType() );
+	}
+
+	private function guessBooleanArg( Arg $arg, Scope $scope, string $key, TrinaryLogic $whenAbsent ): TrinaryLogic {
+		$argsType = $scope->getType( $arg->value );
+		$keyType  = new ConstantStringType( $key );
+
+		$hasKey = $argsType->hasOffsetValueType( $keyType );
+
+		if ( $hasKey->yes() ) {
+			return $argsType->getOffsetValueType( $keyType )->toBoolean()->isTrue();
+		}
+
+		if ( $hasKey->no() ) {
+			return $whenAbsent;
+		}
+
+		return $this->guessBooleanArgFromConstantArrays( $argsType, $key );
+	}
+
+	private function guessBooleanArgFromConstantArrays( Type $argsType, string $key ): TrinaryLogic {
+		$constantArrays = $argsType->getConstantArrays();
+
+		if ( [] === $constantArrays ) {
+			return TrinaryLogic::createMaybe();
+		}
+
+		$knownResult = null;
+
+		foreach ( $constantArrays as $constantArray ) {
+			$result = $this->guessBooleanArgFromConstantArray( $constantArray, $key );
+
+			if ( $result->maybe() ) {
+				continue;
+			}
+
+			if ( null === $knownResult ) {
+				$knownResult = $result;
+				continue;
+			}
+
+			if ( $knownResult->yes() !== $result->yes() ) {
+				return TrinaryLogic::createMaybe();
+			}
+		}
+
+		return $knownResult ?? TrinaryLogic::createMaybe();
+	}
+
+	private function guessBooleanArgFromConstantArray( ConstantArrayType $constantArray, string $key ): TrinaryLogic {
+		foreach ( $constantArray->getKeyTypes() as $index => $argKey ) {
+			if ( ! $this->isConstantStringKey( $argKey, $key ) ) {
+				continue;
+			}
+
+			return $constantArray->getValueTypes()[ $index ]->toBoolean()->isTrue();
+		}
+
+		return TrinaryLogic::createMaybe();
+	}
+
+	private function isConstantStringKey( Type $keyType, string $key ): bool {
+		foreach ( $keyType->getConstantStrings() as $constantString ) {
+			if ( $constantString->getValue() === $key ) {
+				return true;
+			}
+		}
+
+		return false;
+	}
+}
diff --git a/src/GuessTypeFromSwitcherAttributes.php b/src/GuessTypeFromSwitcherAttributes.php
deleted file mode 100644
index 25411ba..0000000
--- a/src/GuessTypeFromSwitcherAttributes.php
+++ /dev/null
@@ -1,76 +0,0 @@
-<?php
-
-namespace WPSyntex\Polylang\PHPStan;
-
-use PhpParser\Node\Expr;
-use PhpParser\Node\Expr\CallLike;
-use PhpParser\Node\Arg;
-use PHPStan\Analyser\Scope;
-use PHPStan\TrinaryLogic;
-use PHPStan\Type\Type;
-use PHPStan\Type\Constant\ConstantStringType;
-use PHPStan\Type\IntersectionType;
-use PHPStan\Type\StringType;
-use PHPStan\Type\ArrayType;
-use PHPStan\Type\MixedType;
-use PHPStan\Type\TypeCombinator;
-
-trait GuessTypeFromSwitcherAttributes {
-	private function guessType(Arg $args, Scope $scope) : Type
-	{
-		$args = $args->value;
-
-		$isRaw = TrinaryLogic::createMaybe();
-
-		if ($args instanceof Expr) {
-			$argsType   = $scope->getType($args);
-			$argsKeys   = [];
-			$argsValues = [];
-
-			if ($argsType->isArray()->yes()) {
-				$argsKeys   = $argsType->getKeysArray();
-				$argsValues = $argsType->getValuesArray();
-			}
-
-			if ($argsType instanceof IntersectionType && $argsType->isIterable()) {
-				// Let's look into each types to see if it contains 'raw' key.
-				$types = $argsType->getTypes();
-				foreach($types as $type) {
-					$rawKey = new ConstantStringType('raw');
-					if ($type->hasOffsetValueType($rawKey)->yes()) {
-						$isRaw = $type->getOffsetValueType($rawKey)->toBoolean()->isTrue();
-					}
-				}
-			}
-
-			if ($argsKeys->isConstantArray()->yes()) {
-				foreach ($argsKeys->getValueTypes() as $index => $key) {
-					if ($key->getValue() !== 'raw') {
-						// Current argument is not 'raw' parameter.
-						continue;
-					}
-					if ($argsValues->getValueTypes()[$index]->getValue()) {
-						// Current argument set 'raw' to 'true'.
-						$isRaw = TrinaryLogic::createYes();
-						break;
-					}
-				}
-				// If none 'raw' parameter set to 'true' is found, consider it's 'false'.
-				$isRaw = $isRaw->yes() ? $isRaw : TrinaryLogic::createNo();
-			}
-		}
-
-		if ($isRaw->maybe()) {
-			// Can't guess type precisely, return 'array<string, mixed>|string'.
-			return TypeCombinator::union(new ArrayType(new StringType(), new MixedType()), new StringType());
-		}
-
-		if ($isRaw->yes()) {
-			// Switcher output is raw, return 'array<string, mixed>'.
-			return new ArrayType(new StringType(), new MixedType());
-		}
-
-		// Raw is considered false, return 'string'.
-		return new StringType();
-	}
-}
diff --git a/src/Rules/DeprecatedPllSwitcherRule.php b/src/Rules/DeprecatedPllSwitcherRule.php
new file mode 100644
index 0000000..6f5a4fd
--- /dev/null
+++ b/src/Rules/DeprecatedPllSwitcherRule.php
@@ -0,0 +1,93 @@
+<?php
+
+namespace WPSyntex\Polylang\PHPStan\Rules;
+
+use PhpParser\Node;
+use PhpParser\Node\Expr;
+use PhpParser\Node\Expr\MethodCall;
+use PhpParser\Node\Expr\New_;
+use PhpParser\Node\Name;
+use PHPStan\Analyser\Scope;
+use PHPStan\Rules\Rule;
+use PHPStan\Rules\RuleError;
+use PHPStan\Rules\RuleErrorBuilder;
+use PHPStan\Type\ObjectType;
+
+/**
+ * Reports usage of PLL_Switcher, removed in Polylang 3.9.
+ *
+ * @implements Rule<Expr>
+ */
+class DeprecatedPllSwitcherRule implements Rule {
+	private const CLASS_NAME = 'PLL_Switcher';
+
+	private const CLASS_MESSAGE = 'Class PLL_Switcher was removed in Polylang 3.9. Use pll_the_languages() or WP_Syntex\Polylang\Switcher\Switcher instead.';
+
+	private const METHOD_MESSAGE = 'Method PLL_Switcher::the_languages() was removed in Polylang 3.9. Use pll_the_languages() instead.';
+
+	public function getNodeType(): string {
+		return Expr::class;
+	}
+
+	public function processNode( Node $node, Scope $scope ): array {
+		if ( ! $node instanceof Expr ) {
+			return [];
+		}
+
+		if ( $node instanceof New_ ) {
+			return $this->processInstantiation( $node );
+		}
+
+		if ( $node instanceof MethodCall ) {
+			return $this->processMethodCall( $node, $scope );
+		}
+
+		return [];
+	}
+
+	/**
+	 * @return list<RuleError>
+	 */
+	private function processInstantiation( New_ $node ): array {
+		if ( ! $node->class instanceof Name ) {
+			return [];
+		}
+
+		if ( self::CLASS_NAME !== $node->class->toString() ) {
+			return [];
+		}
+
+		return [
+			RuleErrorBuilder::message( self::CLASS_MESSAGE )
+				->line( $node->getStartLine() )
+				->identifier( 'polylang.deprecatedSwitcher' )
+				->build(),
+		];
+	}
+
+	/**
+	 * @return list<RuleError>
+	 */
+	private function processMethodCall( MethodCall $node, Scope $scope ): array {
+		if ( ! $node->name instanceof Node\Identifier ) {
+			return [];
+		}
+
+		if ( 'the_languages' !== $node->name->toString() ) {
+			return [];
+		}
+
+		$calledOnType = $scope->getType( $node->var );
+
+		if ( ! ( new ObjectType( self::CLASS_NAME ) )->isSuperTypeOf( $calledOnType )->yes() ) {
+			return [];
+		}
+
+		return [
+			RuleErrorBuilder::message( self::METHOD_MESSAGE )
+				->line( $node->getStartLine() )
+				->identifier( 'polylang.deprecatedSwitcherMethod' )
+				->build(),
+		];
+	}
+}
diff --git a/src/SwitcherClassReturnTypeExtension.php b/src/SwitcherClassReturnTypeExtension.php
deleted file mode 100644
index 10fbc2d..0000000
--- a/src/SwitcherClassReturnTypeExtension.php
+++ /dev/null
@@ -1,46 +0,0 @@
-<?php
-
-namespace WPSyntex\Polylang\PHPStan;
-
-use WPSyntex\Polylang\PHPStan\GuessTypeFromSwitcherAttributes;
-use PhpParser\Node\Expr\MethodCall;
-use PHPStan\Type\DynamicMethodReturnTypeExtension;
-use PHPStan\Reflection\ParametersAcceptorSelector;
-use PHPStan\Analyser\Scope;
-use PHPStan\Reflection\MethodReflection;
-use PHPStan\Type\Type;
-use PHPStan\Type\StringType;
-
-class SwitcherClassReturnTypeExtension implements DynamicMethodReturnTypeExtension {
-	use GuessTypeFromSwitcherAttributes;
-
-	public function getClass(): string
-	{
-		return \PLL_Switcher::class;
-	}
-
-	public function isMethodSupported(MethodReflection $methodReflection): bool
-	{
-		return $methodReflection->getName() === 'the_languages';
-	}
-
-	public function getTypeFromMethodCall(MethodReflection $methodReflection, MethodCall $methodCall, Scope $scope): Type
-	{
-		$args = $methodCall->getArgs();
-
-		if (count($args) === 0) {
-			return ParametersAcceptorSelector::selectFromArgs(
-				$scope,
-				$methodCall->getArgs(),
-				$methodReflection->getVariants()
-			)->getReturnType();
-		}
-
-		if(isset($args[1])) {
-			return $this->guessType($args[1], $scope);
-		}
-
-		// No attributes provided to the switcher, default type 'string'.
-		return new StringType();
-	}
-}
diff --git a/src/TheLanguagesFunctionReturnTypeExtension.php b/src/TheLanguagesFunctionReturnTypeExtension.php
index e4ee74a..2cafe45 100644
--- a/src/TheLanguagesFunctionReturnTypeExtension.php
+++ b/src/TheLanguagesFunctionReturnTypeExtension.php
@@ -2,34 +2,27 @@
 
 namespace WPSyntex\Polylang\PHPStan;
 
-use WPSyntex\Polylang\PHPStan\GuessTypeFromSwitcherAttributes;
 use PhpParser\Node\Expr\FuncCall;
+use PHPStan\Analyser\Scope;
 use PHPStan\Reflection\FunctionReflection;
 use PHPStan\Type\DynamicFunctionReturnTypeExtension;
-use PHPStan\Reflection\ParametersAcceptorSelector;
-use PHPStan\Analyser\Scope;
 use PHPStan\Type\Type;
-use PHPStan\Type\StringType;
+use PHPStan\Type\VoidType;
 
 class TheLanguagesFunctionReturnTypeExtension implements DynamicFunctionReturnTypeExtension {
-	use GuessTypeFromSwitcherAttributes;
+	use GuessTypeFromSwitcherArgs;
 
-	public function isFunctionSupported(FunctionReflection $functionReflection): bool
-	{
-		return $functionReflection->getName() === 'pll_the_languages';
+	public function isFunctionSupported( FunctionReflection $functionReflection ): bool {
+		return 'pll_the_languages' === $functionReflection->getName();
 	}
 
-	public function getTypeFromFunctionCall(FunctionReflection $functionReflection, FuncCall $funcCall, Scope $scope): Type
-	{
+	public function getTypeFromFunctionCall( FunctionReflection $functionReflection, FuncCall $funcCall, Scope $scope ): Type {
 		$args = $funcCall->getArgs();
 
-		if (count($args) === 0) {
-			// No attributes provided to the switcher, default type 'string'.
-			return new StringType();
+		if ( 0 === count( $args ) ) {
+			return new VoidType();
 		}
 
-		$switcherAttributes = reset($args);
-
-		return $this->guessType($switcherAttributes, $scope);
+		return $this->guessPllTheLanguagesReturnType( reset( $args ), $scope );
 	}
 }
diff --git a/stubs/pll-switcher-deprecated.php b/stubs/pll-switcher-deprecated.php
new file mode 100644
index 0000000..500b766
--- /dev/null
+++ b/stubs/pll-switcher-deprecated.php
@@ -0,0 +1,22 @@
+<?php
+
+/**
+ * Deprecated API kept for static analysis only.
+ *
+ * @package Polylang
+ */
+
+/**
+ * @deprecated 3.9 Removed. Use pll_the_languages() or WP_Syntex\Polylang\Switcher\Switcher.
+ */
+class PLL_Switcher {
+	/**
+	 * @deprecated 3.9 Use pll_the_languages() instead.
+	 *
+	 * @param PLL_Links $links Instance of PLL_Links.
+	 * @param array     $args  Optional array of arguments.
+	 * @return string|array<string, mixed>
+	 */
+	public function the_languages( $links, $args = array() ) {
+	}
+}
diff --git a/tests/DeprecatedApiTest.php b/tests/DeprecatedApiTest.php
new file mode 100644
index 0000000..c1ff9d3
--- /dev/null
+++ b/tests/DeprecatedApiTest.php
@@ -0,0 +1,37 @@
+<?php
+
+declare(strict_types=1);
+
+namespace WPSyntex\Polylang\PHPStan\Tests;
+
+use PHPStan\Rules\Rule;
+use WPSyntex\Polylang\PHPStan\Rules\DeprecatedPllSwitcherRule;
+
+class DeprecatedApiTest extends \PHPStan\Testing\RuleTestCase {
+	protected function getRule(): Rule {
+		return new DeprecatedPllSwitcherRule();
+	}
+
+	public function testPllSwitcherUsageIsReportedAsDeprecated(): void {
+		$this->analyse(
+			[ __DIR__ . '/data/deprecated_pll_switcher.php' ],
+			[
+				[
+					'Class PLL_Switcher was removed in Polylang 3.9. Use pll_the_languages() or WP_Syntex\Polylang\Switcher\Switcher instead.',
+					11,
+				],
+				[
+					'Method PLL_Switcher::the_languages() was removed in Polylang 3.9. Use pll_the_languages() instead.',
+					13,
+				],
+			]
+		);
+	}
+
+	public static function getAdditionalConfigFiles(): array {
+		return [
+			__DIR__ . '/phpstan.neon',
+			__DIR__ . '/test-extension.neon',
+		];
+	}
+}
diff --git a/tests/DynamicReturnTypeExtensionTest.php b/tests/DynamicReturnTypeExtensionTest.php
index 6984e8c..d266550 100644
--- a/tests/DynamicReturnTypeExtensionTest.php
+++ b/tests/DynamicReturnTypeExtensionTest.php
@@ -4,35 +4,29 @@
 
 namespace WPSyntex\Polylang\PHPStan\Tests;
 
-class DynamicReturnTypeExtensionTest extends \PHPStan\Testing\TypeInferenceTestCase
-{
+class DynamicReturnTypeExtensionTest extends \PHPStan\Testing\TypeInferenceTestCase {
 	/**
 	 * @return iterable<mixed>
 	 */
-	public function dataFileAsserts(): iterable
-	{
-		// Path to a file with actual asserts of expected types:
-		yield from $this->gatherAssertTypes(__DIR__ . '/data/the_languages.php');
-		yield from $this->gatherAssertTypes(__DIR__ . '/data/pll_the_languages.php');
-		yield from $this->gatherAssertTypes(__DIR__ . '/data/get_languages_list.php');
-		yield from $this->gatherAssertTypes(__DIR__ . '/data/options_get.php');
+	public function dataFileAsserts(): iterable {
+		yield from $this->gatherAssertTypes( __DIR__ . '/data/pll_the_languages.php' );
+		yield from $this->gatherAssertTypes( __DIR__ . '/data/switcher.php' );
+		yield from $this->gatherAssertTypes( __DIR__ . '/data/get_languages_list.php' );
+		yield from $this->gatherAssertTypes( __DIR__ . '/data/options_get.php' );
 	}
 
 	/**
 	 * @dataProvider dataFileAsserts
 	 * @param array<string> ...$args
 	 */
-	public function testFileAsserts(string $assertType, string $file, ...$args): void
-	{
-		$this->assertFileAsserts($assertType, $file, ...$args);
+	public function testFileAsserts( string $assertType, string $file, ...$args ): void {
+		$this->assertFileAsserts( $assertType, $file, ...$args );
 	}
 
-	public static function getAdditionalConfigFiles(): array
-	{
-		// phpstan.neon or extension.neon use relative paths, so we need to use a fake vendor directory regarding szepeviktor/phpstan-wordpress dependency.
+	public static function getAdditionalConfigFiles(): array {
 		return [
-			dirname(__DIR__) . '/vendor/wpsyntex/polylang-phpstan/extension.neon',
-			dirname(__DIR__) . '/vendor/wpsyntex/polylang-phpstan/test-extension.neon',
+			__DIR__ . '/phpstan.neon',
+			__DIR__ . '/test-extension.neon',
 		];
 	}
 }
diff --git a/tests/data/deprecated_pll_switcher.php b/tests/data/deprecated_pll_switcher.php
new file mode 100644
index 0000000..08f0249
--- /dev/null
+++ b/tests/data/deprecated_pll_switcher.php
@@ -0,0 +1,13 @@
+<?php
+
+declare(strict_types=1);
+
+namespace WPSyntex\Polylang\PHPStan\Tests;
+
+/** @var \PLL_Links $links */
+$links = $links;
+
+/** @var \PLL_Switcher $switcher */
+$switcher = new \PLL_Switcher();
+
+$switcher->the_languages( $links, [ 'raw' => true ] );
diff --git a/tests/data/pll_the_languages.php b/tests/data/pll_the_languages.php
index 1876615..aa6053b 100644
--- a/tests/data/pll_the_languages.php
+++ b/tests/data/pll_the_languages.php
@@ -6,46 +6,45 @@
 
 use function PHPStan\Testing\assertType;
 
-/** @var \PLL_Links */
-$link = $link;
-
 /** @var array */
 $array = $array;
 
-$attributes = ['foo' => 'bar'];
-
-// Raw attribute set to true.
-assertType('array<string, mixed>', pll_the_languages(['raw' => true]));
-
-// Raw attribute set to true with array_merge.
-assertType('array<string, mixed>', pll_the_languages(array_merge($attributes, ['raw' => true])));
+/** @var array<string, mixed> */
+$options = $options;
 
-// Raw attribute set to false.
-assertType('string', pll_the_languages(['raw' => false]));
+$attributes = [ 'foo' => 'bar' ];
 
-// Raw attribute set to false with array_merge and variable with known values.
-assertType('string', pll_the_languages(array_merge($attributes, ['raw' => false])));
+// raw => true
+assertType( 'array<string, mixed>', pll_the_languages( [ 'raw' => true ] ) );
+assertType( 'array<string, mixed>', pll_the_languages( array_merge( $attributes, [ 'raw' => true ] ) ) );
 
-// Without raw set.
-assertType('string', pll_the_languages($attributes));
+// echo => false
+assertType( 'string', pll_the_languages( [ 'echo' => false ] ) );
+assertType( 'string', pll_the_languages( [ 'raw' => false, 'echo' => false ] ) );
+assertType( 'string', pll_the_languages( array_merge( $attributes, [ 'echo' => false ] ) ) );
 
-// With empty array.
-assertType('string', pll_the_languages([]));
-
-// Default attributes.
-assertType('string', pll_the_languages());
+// Default: echo is true, nothing is returned.
+assertType( 'void', pll_the_languages() );
+assertType( 'void', pll_the_languages( [] ) );
+assertType( 'void', pll_the_languages( $attributes ) );
+assertType( 'void', pll_the_languages( [ 'raw' => false ] ) );
+assertType( 'void', pll_the_languages( array_merge( $attributes, [ 'raw' => false ] ) ) );
 
 // Unknown attributes.
-assertType('array<string, mixed>|string', pll_the_languages($array));
+assertType( 'array<string, mixed>|string|void', pll_the_languages( $array ) );
 
 // With unknown variable merged.
 $args = array_merge( [ 'raw' => 1 ], $options );
-assertType('array<string, mixed>|string', pll_the_languages($args));
+assertType( 'array<string, mixed>|string|void', pll_the_languages( $args ) );
 
 // With raw attribute set to true outside.
 $array['raw'] = 1;
-assertType('array<string, mixed>', pll_the_languages($array));
+assertType( 'array<string, mixed>', pll_the_languages( $array ) );
 
-// With raw attribute set to false outside.
+// With raw attribute set to false outside a previously unknown array.
 $array['raw'] = false;
-assertType('string', pll_the_languages($array));
+assertType( 'string|void', pll_the_languages( $array ) );
+
+// With echo attribute set to false outside.
+$array['echo'] = false;
+assertType( 'string', pll_the_languages( $array ) );
diff --git a/tests/data/switcher.php b/tests/data/switcher.php
new file mode 100644
index 0000000..b4c4e88
--- /dev/null
+++ b/tests/data/switcher.php
@@ -0,0 +1,20 @@
+<?php
+
+declare(strict_types=1);
+
+namespace WPSyntex\Polylang\PHPStan\Tests;
+
+use WP_Syntex\Polylang\Switcher\Switcher;
+use WP_Syntex\Polylang\Switcher\Settings\Settings;
+use function PHPStan\Testing\assertType;
+
+/** @var Settings $settings */
+$settings = $settings;
+
+/** @var \PLL_Links $links */
+$links = $links;
+
+$switcher = new Switcher( $settings, $links );
+
+assertType( 'string', $switcher->get() );
+assertType( 'array<WP_Syntex\Polylang\Switcher\Element\Abstract_Element>', $switcher->get_elements() );
diff --git a/tests/data/the_languages.php b/tests/data/the_languages.php
deleted file mode 100644
index 5fde6af..0000000
--- a/tests/data/the_languages.php
+++ /dev/null
@@ -1,66 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-namespace WPSyntex\Polylang\PHPStan\Tests;
-
-use function PHPStan\Testing\assertType;
-
-/** @var \PLL_Switcher */
-$switcher = $switcher;
-
-/** @var \PLL_Links */
-$link = $link;
-
-/** @var array */
-$array = $array;
-
-$attributes = ['foo' => 'bar'];
-
-// Raw attribute set to true.
-assertType('array<string, mixed>', $switcher->the_languages($link, ['raw' => true]));
-
-// Raw attribute set tot true with array_merge.
-assertType('array<string, mixed>', $switcher->the_languages($link, array_merge($attributes, ['raw' => true])));
-
-// Raw attribute set to false.
-assertType('string', $switcher->the_languages($link, ['raw' => false]));
-
-// Raw attribute set to false with array_merge.
-assertType('string', $switcher->the_languages($link, array_merge($attributes, ['raw' => false])));
-
-// Without raw set.
-assertType('string', $switcher->the_languages($link, $attributes));
-
-// With empty array.
-assertType('string', $switcher->the_languages($link, []));
-
-// Default attributes.
-assertType('string', $switcher->the_languages($link));
-
-// Unknown attributes.
-assertType('array<string, mixed>|string', $switcher->the_languages($link, $array));
-
-// With raw attribute set to true and merged into an array.
-$args = array_merge( $array, [ 'raw' => 1 ] );
-assertType('array<string, mixed>', $switcher->the_languages($link, $args));
-
-// With raw attribute set to true and merged with an array.
-$args = array_merge( [ 'raw' => true ], $array );
-assertType('array<string, mixed>|string', $switcher->the_languages($link, $args));
-
-// With raw attribute set to true outside.
-$array['raw'] = 1;
-assertType('array<string, mixed>', $switcher->the_languages($link, $array));
-
-// With raw attribute set to false outside.
-$array['raw'] = false;
-assertType('string', $switcher->the_languages($link, $array));
-
-// With raw attribute set to false and merged in an array.
-$args = array_merge( $array, [ 'raw' => false ] );
-assertType('string', $switcher->the_languages($link, $array));
-
-// With raw attribute set to false and merged with an array.
-$args = array_merge( [ 'raw' => false ], $array );
-assertType('string', $switcher->the_languages($link, $array));
diff --git a/tests/phpstan.neon b/tests/phpstan.neon
new file mode 100644
index 0000000..3a45a48
--- /dev/null
+++ b/tests/phpstan.neon
@@ -0,0 +1,40 @@
+includes:
+	- ../vendor/szepeviktor/phpstan-wordpress/extension.neon
+
+services:
+	-
+		class: WPSyntex\Polylang\PHPStan\LanguageReturnTypeExtension
+		tags:
+			- phpstan.broker.dynamicFunctionReturnTypeExtension
+	-
+		class: WPSyntex\Polylang\PHPStan\TheLanguagesFunctionReturnTypeExtension
+		tags:
+			- phpstan.broker.dynamicFunctionReturnTypeExtension
+	-
+		class: WPSyntex\Polylang\PHPStan\PLLModelGetLanguagesListDynamicMethodReturnTypeExtension
+		tags:
+			- phpstan.broker.dynamicMethodReturnTypeExtension
+	-
+		class: WPSyntex\Polylang\PHPStan\ModelLanguagesGetListDynamicMethodReturnTypeExtension
+		tags:
+			- phpstan.broker.dynamicMethodReturnTypeExtension
+	-
+		class: WPSyntex\Polylang\PHPStan\OptionsGetDynamicMethodReturnTypeExtension
+		tags:
+			- phpstan.broker.dynamicMethodReturnTypeExtension
+	-
+		class: WPSyntex\Polylang\PHPStan\Rules\DeprecatedPllSwitcherRule
+		tags:
+			- phpstan.rules.rule
+
+parameters:
+	bootstrapFiles:
+		- ../bootstrap.php
+	stubFiles:
+		- ../vendor/php-stubs/wordpress-stubs/wordpress-stubs.php
+	scanFiles:
+		- ../stubs/pll-switcher-deprecated.php
+	dynamicConstantNames:
+		- POLYLANG_VERSION
+		- PLL_ADMIN
+		- PLL_SETTINGS