diff --git a/src/Psl/Collection/MutableSet.php b/src/Psl/Collection/MutableSet.php
index 21eda1f6..18a1aa2e 100644
--- a/src/Psl/Collection/MutableSet.php
+++ b/src/Psl/Collection/MutableSet.php
@@ -76,13 +76,18 @@ public static function fromArray(array $elements): MutableSet
      *
      * @template Ts of array-key
      *
-     * @param iterable<Ts> $items
+     * @param iterable<Ts, Ts> $items
      *
      * @return MutableSet<Ts>
      */
     public static function fromItems(iterable $items): MutableSet
     {
-        return self::fromArray(iterator_to_array($items));
+        /**
+         * @psalm-suppress InvalidArgument
+         * @var array<Ts, Ts>
+         */
+        $array = iterator_to_array($items);
+        return self::fromArray($array);
     }
 
     /**
diff --git a/src/Psl/Collection/MutableVector.php b/src/Psl/Collection/MutableVector.php
index 76915ca0..bd550254 100644
--- a/src/Psl/Collection/MutableVector.php
+++ b/src/Psl/Collection/MutableVector.php
@@ -75,13 +75,18 @@ public static function fromArray(array $elements): MutableVector
      *
      * @template Ts
      *
-     * @param iterable<Ts> $items
+     * @param iterable<array-key, Ts> $items
      *
      * @return MutableVector<Ts>
      */
     public static function fromItems(iterable $items): MutableVector
     {
-        return self::fromArray(iterator_to_array($items));
+        /**
+         * @psalm-suppress InvalidArgument
+         * @var array<array-key, Ts>
+         */
+        $array = iterator_to_array($items);
+        return self::fromArray($array);
     }
 
     /**
diff --git a/src/Psl/Collection/Set.php b/src/Psl/Collection/Set.php
index 981b4785..bd93ba82 100644
--- a/src/Psl/Collection/Set.php
+++ b/src/Psl/Collection/Set.php
@@ -77,15 +77,18 @@ public static function fromArray(array $elements): Set
      *
      * @template Ts of array-key
      *
-     * @param iterable<Ts, mixed> $items
+     * @param iterable<array-key, Ts> $items
      *
      * @return Set<Ts>
-     *
-     * @pure
      */
     public static function fromItems(iterable $items): Set
     {
-        return self::fromArray(iterator_to_array($items));
+        /**
+         * @var array<array-key, Ts>
+         * @psalm-suppress InvalidArgument
+         */
+        $array = iterator_to_array($items);
+        return self::fromArray($array);
     }
 
     /**
diff --git a/src/Psl/Collection/Vector.php b/src/Psl/Collection/Vector.php
index 1f4e9ba7..3a1cf868 100644
--- a/src/Psl/Collection/Vector.php
+++ b/src/Psl/Collection/Vector.php
@@ -74,13 +74,18 @@ public static function fromArray(array $elements): Vector
      *
      * @template Ts
      *
-     * @param iterable<Ts> $items
+     * @param iterable<array-key, Ts> $items
      *
      * @return Vector<Ts>
      */
     public static function fromItems(iterable $items): Vector
     {
-        return self::fromArray(iterator_to_array($items));
+        /**
+         * @psalm-suppress InvalidArgument
+         * @var array<array-key, Ts>
+         */
+        $array = iterator_to_array($items);
+        return self::fromArray($array);
     }
 
     /**