diff --git a/CHANGELOG.md b/CHANGELOG.md
index 86e2335..7c9b2c7 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,6 +8,9 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 ### Changed
 - Aligned param names with those of PSR interfaces (#37).
 - Added more generics (#38).
+- Added `mixed` typehints where missing (#38).
+- Factories now return Dhii `ContainerInterface` (#39).
+  A small inconvenience for type safety.
 
 ## [0.5.0-beta1] - 2026-03-23
 ### Changed
diff --git a/src/ContainerFactoryInterface.php b/src/ContainerFactoryInterface.php
index d6349c5..656b421 100644
--- a/src/ContainerFactoryInterface.php
+++ b/src/ContainerFactoryInterface.php
@@ -5,7 +5,6 @@
 namespace Dhii\Collection;
 
 use Exception;
-use Psr\Container\ContainerInterface;
 
 /**
  * Creates containers based on data maps.
@@ -15,9 +14,12 @@ interface ContainerFactoryInterface
     /**
      * Creates a container based on data.
      *
-     * @param array<string, mixed> $data The data for the container.
+     * @template K of string
+     * @template V of mixed
      *
-     * @return ContainerInterface The new container.
+     * @param array<K, V> $data The data for the container.
+     *
+     * @return ContainerInterface<K, V> The new container.
      *
      * @throws Exception If problem creating.
      *
diff --git a/src/MapFactoryInterface.php b/src/MapFactoryInterface.php
index 816436f..dc21463 100644
--- a/src/MapFactoryInterface.php
+++ b/src/MapFactoryInterface.php
@@ -16,9 +16,12 @@ interface MapFactoryInterface extends ContainerFactoryInterface
     /**
      * Creates a map based on data in an array.
      *
-     * @param array<string, mixed> $data The data to base the map on.
+     * @template K of string
+     * @template V of mixed
      *
-     * @return MapInterface The new map.
+     * @param array<K, V> $data The data for the container.
+     *
+     * @return MapInterface<K, V> The new container.
      *
      * @throws Exception If problem creating.
      */
diff --git a/src/WritableContainerFactoryInterface.php b/src/WritableContainerFactoryInterface.php
index 364ea17..bbc1ff8 100644
--- a/src/WritableContainerFactoryInterface.php
+++ b/src/WritableContainerFactoryInterface.php
@@ -4,8 +4,6 @@
 
 namespace Dhii\Collection;
 
-use Psr\Container\ContainerInterface;
-
 /**
  * A map that can create a writable container.
  */