diff --git a/composer.json b/composer.json
index 35489ea..adcfc45 100644
--- a/composer.json
+++ b/composer.json
@@ -19,12 +19,12 @@
     },
     "require-dev": {
         "ext-simplexml": "*",
-        "phpunit/phpunit": "^9.0",
-        "php-coveralls/php-coveralls": "^2.2",
         "friendsofphp/php-cs-fixer": "^2.16",
+        "php-coveralls/php-coveralls": "^2.2",
+        "phpunit/phpunit": "^9.0",
         "roave/security-advisories": "dev-master",
         "squizlabs/php_codesniffer": "^3.5",
-        "vimeo/psalm": "dev-master"
+        "vimeo/psalm": "^4.0"
     },
     "autoload": {
         "psr-4": {
diff --git a/src/Psl/Xml/Issue/IssueCollection.php b/src/Psl/Xml/Issue/IssueCollection.php
index 714331d..75a6fdd 100644
--- a/src/Psl/Xml/Issue/IssueCollection.php
+++ b/src/Psl/Xml/Issue/IssueCollection.php
@@ -13,8 +13,6 @@ use Psl\Str;
 
 /**
  * @template-implements IteratorAggregate<int, Issue>
- *
- * @psalm-immutable
  */
 final class IssueCollection implements Countable, IteratorAggregate
 {