diff --git a/src/Map/DisplayMap/DisplayMapRenderer.php b/src/Map/DisplayMap/DisplayMapRenderer.php
index a723e5f1..97ecf2f3 100644
--- a/src/Map/DisplayMap/DisplayMapRenderer.php
+++ b/src/Map/DisplayMap/DisplayMapRenderer.php
@@ -31,7 +31,7 @@ class DisplayMapRenderer {
 	private WikitextParser $wikitextParser;
 	private ElementJsonSerializer $elementSerializer;
 
-	public function __construct( MappingService $service = null ) {
+	public function __construct( ?MappingService $service = null ) {
 		$this->service = $service;
 	}
 
diff --git a/src/Presentation/MapsDistanceParser.php b/src/Presentation/MapsDistanceParser.php
index 262b837a..934ee3da 100644
--- a/src/Presentation/MapsDistanceParser.php
+++ b/src/Presentation/MapsDistanceParser.php
@@ -17,14 +17,14 @@ class MapsDistanceParser {
 	private static bool $validatedDistanceUnit = false;
 	private static $unitRegex = false;
 
-	public static function parseAndFormat( string $distance, string $unit = null, int $decimals = 2 ): string {
+	public static function parseAndFormat( string $distance, ?string $unit = null, int $decimals = 2 ): string {
 		return self::formatDistance( self::parseDistance( $distance ), $unit, $decimals );
 	}
 
 	/**
 	 * Formats a given distance in meters to a distance in an optionally specified notation.
 	 */
-	public static function formatDistance( float $meters, string $unit = null, int $decimals = 2 ): string {
+	public static function formatDistance( float $meters, ?string $unit = null, int $decimals = 2 ): string {
 		$meters = MediaWikiServices::getInstance()->getContentLanguage()->formatNum( round( $meters / self::getUnitRatio( $unit ), $decimals ) );
 		return "$meters $unit";
 	}
@@ -32,7 +32,7 @@ public static function formatDistance( float $meters, string $unit = null, int $
 	/**
 	 * Returns the unit to meter ratio in a safe way, by first resolving the unit.
 	 */
-	public static function getUnitRatio( string $unit = null ): float {
+	public static function getUnitRatio( ?string $unit = null ): float {
 		global $egMapsDistanceUnits;
 		return $egMapsDistanceUnits[self::getValidUnit( $unit )];
 	}
@@ -40,7 +40,7 @@ public static function getUnitRatio( string $unit = null ): float {
 	/**
 	 * Returns a valid unit. If the provided one is invalid, the default will be used.
 	 */
-	public static function getValidUnit( string $unit = null ): string {
+	public static function getValidUnit( ?string $unit = null ): string {
 		global $egMapsDistanceUnit, $egMapsDistanceUnits;
 
 		// This ensures the value for $egMapsDistanceUnit is correct, and caches the result.
diff --git a/src/SemanticMW/AreaDescription.php b/src/SemanticMW/AreaDescription.php
index 4393b3bc..13a8b145 100644
--- a/src/SemanticMW/AreaDescription.php
+++ b/src/SemanticMW/AreaDescription.php
@@ -29,7 +29,7 @@ class AreaDescription extends ValueDescription {
 	private SMWDIGeoCoord $center;
 	private string $radius;
 
-	public function __construct( SMWDataItem $areaCenter, int $comparator, string $radius, DIProperty $property = null ) {
+	public function __construct( SMWDataItem $areaCenter, int $comparator, string $radius, ?DIProperty $property = null ) {
 		if ( !( $areaCenter instanceof SMWDIGeoCoord ) ) {
 			throw new InvalidArgumentException( '$areaCenter needs to be a SMWDIGeoCoord' );
 		}
diff --git a/src/SemanticMW/CoordinateValue.php b/src/SemanticMW/CoordinateValue.php
index 014951f1..52ee2c1e 100644
--- a/src/SemanticMW/CoordinateValue.php
+++ b/src/SemanticMW/CoordinateValue.php
@@ -160,7 +160,7 @@ public function getShortWikiText( $linker = null ) {
 	 *
 	 * @return string|null
 	 */
-	private function getFormattedCoord( SMWDIGeoCoord $dataItem, string $format = null ) {
+	private function getFormattedCoord( SMWDIGeoCoord $dataItem, ?string $format = null ) {
 		return MapsFactory::globalInstance()->getCoordinateFormatter()->format(
 			new LatLongValue(
 				$dataItem->getLatitude(),