diff --git a/composer.json b/composer.json
index 99270e3..c0f7dd3 100644
--- a/composer.json
+++ b/composer.json
@@ -7,8 +7,8 @@
     },
     "require-dev": {
         "phpunit/phpunit": "^9.5",
-        "vimeo/psalm": "^4.7",
-        "psalm/plugin-phpunit": "^0.17",
+        "vimeo/psalm": "^5",
+        "psalm/plugin-phpunit": "^0.18",
         "squizlabs/php_codesniffer": "^3.6"
     },
     "autoload": {
diff --git a/psalm.xml b/psalm.xml
index 550298b..0b8cb4c 100644
--- a/psalm.xml
+++ b/psalm.xml
@@ -4,6 +4,8 @@
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xmlns="https://getpsalm.org/schema/config"
     xsi:schemaLocation="https://getpsalm.org/schema/config https://raw.githubusercontent.com/vimeo/psalm/master/config.xsd"
+    findUnusedBaselineEntry="true"
+    findUnusedCode="false"
 >
     <projectFiles>
         <directory name="src"/>
diff --git a/src/Error.php b/src/Error.php
index 44ef760..69c3be1 100644
--- a/src/Error.php
+++ b/src/Error.php
@@ -43,6 +43,12 @@ public function get()
         return $this->value;
     }
 
+    /**
+     * @template TNewError
+     *
+     * @param callable(TError):TNewError $map
+     * @return TNewError
+     */
     public function getOr(callable $map)
     {
         return $map($this->value);
diff --git a/src/None.php b/src/None.php
index 09c0509..4b3bfc1 100644
--- a/src/None.php
+++ b/src/None.php
@@ -20,11 +20,21 @@ public function flatMap(callable $map): Option
         return $this;
     }
 
+    /**
+     * @template TElse
+     * @param callable():TElse $else
+     * @return TElse
+     */
     public function getOr(callable $else)
     {
         return $else();
     }
 
+    /**
+     * @template TElse
+     * @param TElse $else
+     * @return TElse
+     */
     public function getOrElse($else)
     {
         return $else;
diff --git a/test/ResultTest.php b/test/ResultTest.php
index a8921f0..0b73be2 100644
--- a/test/ResultTest.php
+++ b/test/ResultTest.php
@@ -191,6 +191,7 @@ public function testEnsureSuccessReturningFalse(): void
     public function testEnsureErrorDoesNotChangePreviousError(): void
     {
         $result = Result::error('old error');
+        /** @psalm-var Result $result */
         $ensured = $result->ensure(fn(int $i) => $i > 100, 'new error');
         self::assertEquals('old error', $ensured->get());
     }