diff --git a/src/PluginManagerInterface.php b/src/PluginManagerInterface.php
index 1daa4665..156da327 100644
--- a/src/PluginManagerInterface.php
+++ b/src/PluginManagerInterface.php
@@ -11,6 +11,8 @@
  * Interface for a plugin manager
  *
  * A plugin manager is a specialized service locator used to create homogeneous objects
+ *
+ * @template InstanceType of object
  */
 interface PluginManagerInterface extends ServiceLocatorInterface
 {
@@ -22,6 +24,7 @@ interface PluginManagerInterface extends ServiceLocatorInterface
      * @throws InvalidServiceException If created instance does not respect the
      *     constraint on type imposed by the plugin manager.
      * @throws ContainerExceptionInterface If any other error occurs.
+     * @psalm-assert InstanceType $instance
      */
     public function validate($instance);
 }