diff --git a/src/Option.php b/src/Option.php
index be6c96e..fcef59e 100644
--- a/src/Option.php
+++ b/src/Option.php
@@ -35,6 +35,7 @@ public static function none(): None
     }
 
     /**
+     * @psalm-pure
      * @template TNew
      * @param TNew|null $value
      * @return Option<TNew>
@@ -47,6 +48,7 @@ public static function fromNullable($value): Option
     }
 
     /**
+     * @psalm-pure
      * @template T
      * @param list<Option<T>> $options
      * @return Option<list<T>>
diff --git a/src/Result.php b/src/Result.php
index 138a0be..d5cad2c 100644
--- a/src/Result.php
+++ b/src/Result.php
@@ -37,6 +37,7 @@ public static function error($value): Error
     /**
      * Filters and extracts values only of Success results from the given array.
      *
+     * @psalm-pure
      * @template S
      * @param list<ResultInterface<S, mixed>> $results
      * @return list<S>
@@ -67,6 +68,7 @@ public static function extractSuccesses(array $results): array
     /**
      * Filters and extracts values only of Error results from the given array.
      *
+     * @psalm-pure
      * @template E
      * @param list<ResultInterface<mixed, E>> $results
      * @return list<E>