diff --git a/CHANGELOG.md b/CHANGELOG.md
index 711be85ff..7d0d92f4d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -32,7 +32,7 @@ Please also have a look at our
 - Make all non-private properties `@internal` (#886)
 - Use more native type declarations and strict mode
   (#641, #772, #774, #778, #804, #841, #873, #875, #891, #922, #923, #933, #958,
-  #964, #967, #1000, #1044, #1134)
+  #964, #967, #1000, #1044, #1134, #1137, #1139)
 - Add visibility to all class/interface constants (#469)
 
 ### Deprecated
diff --git a/src/CSSList/CSSList.php b/src/CSSList/CSSList.php
index 3c5385936..1af21f852 100644
--- a/src/CSSList/CSSList.php
+++ b/src/CSSList/CSSList.php
@@ -245,10 +245,8 @@ private static function parseAtRule(ParserState $parserState)
     /**
      * Tests an identifier for a given value. Since identifiers are all keywords, they can be vendor-prefixed.
      * We need to check for these versions too.
-     *
-     * @param string $identifier
      */
-    private static function identifierIs($identifier, string $match): bool
+    private static function identifierIs(string $identifier, string $match): bool
     {
         return (\strcasecmp($identifier, $match) === 0)
             ?: \preg_match("/^(-\\w+-)?$match$/i", $identifier) === 1;
diff --git a/src/CSSList/Document.php b/src/CSSList/Document.php
index 2051d3c2a..f50c166f1 100644
--- a/src/CSSList/Document.php
+++ b/src/CSSList/Document.php
@@ -42,7 +42,7 @@ public static function parse(ParserState $parserState): Document
      *
      * @see RuleSet->getRules()
      */
-    public function getAllValues($element = null, $searchInFunctionArguments = false): array
+    public function getAllValues($element = null, bool $searchInFunctionArguments = false): array
     {
         $searchString = null;
         if ($element === null) {
@@ -70,7 +70,7 @@ public function getAllValues($element = null, $searchInFunctionArguments = false
      * @return array<int, Selector>
      * @example `getSelectorsBySpecificity('>= 100')`
      */
-    public function getSelectorsBySpecificity($specificitySearch = null): array
+    public function getSelectorsBySpecificity(?string $specificitySearch = null): array
     {
         /** @var array<int, Selector> $result */
         $result = [];
diff --git a/src/Value/Value.php b/src/Value/Value.php
index 27840cc3a..a81ab472c 100644
--- a/src/Value/Value.php
+++ b/src/Value/Value.php
@@ -109,8 +109,6 @@ public static function parseValue(ParserState $parserState, array $listDelimiter
     }
 
     /**
-     * @param bool $ignoreCase
-     *
      * @return CSSFunction|string
      *
      * @throws UnexpectedEOFException
@@ -118,7 +116,7 @@ public static function parseValue(ParserState $parserState, array $listDelimiter
      *
      * @internal since V8.8.0
      */
-    public static function parseIdentifierOrFunction(ParserState $parserState, $ignoreCase = false)
+    public static function parseIdentifierOrFunction(ParserState $parserState, bool $ignoreCase = false)
     {
         $anchor = $parserState->anchor();
         $result = $parserState->parseIdentifier($ignoreCase);