diff --git a/hardware_interface/doc/mock_components_userdoc.rst b/hardware_interface/doc/mock_components_userdoc.rst
index 7e5a997a21..5663fd0350 100644
--- a/hardware_interface/doc/mock_components_userdoc.rst
+++ b/hardware_interface/doc/mock_components_userdoc.rst
@@ -22,6 +22,7 @@ Features:
   - support for mimic joints, which is parsed from the URDF (see the `URDF wiki <http://wiki.ros.org/urdf/XML/joint>`__)
   - mirroring commands to states with and without offset
   - fake command interfaces for setting sensor data from an external node (combined with a :ref:`forward controller <forward_command_controller_userdoc>`)
+  - fake gpio interfaces for setting sensor data from an external node (combined with a :ref:`forward controller <forward_command_controller_userdoc>`)
 
 
 Parameters
@@ -36,6 +37,10 @@ mock_sensor_commands (optional; boolean; default: false)
   Creates fake command interfaces for faking sensor measurements with an external command.
   Those interfaces are usually used by a :ref:`forward controller <forward_command_controller_userdoc>` to provide access from ROS-world.
 
+mock_gpio_commands (optional; boolean; default: false)
+  Creates fake command interfaces for faking GPIO states with an external command.
+  Those interfaces are usually used by a :ref:`forward controller <forward_command_controller_userdoc>` to provide access from ROS-world.
+
 position_state_following_offset (optional; double; default: 0.0)
   Following offset added to the commanded values when mirrored to states.
 
diff --git a/hardware_interface/src/mock_components/generic_system.cpp b/hardware_interface/src/mock_components/generic_system.cpp
index 5e5165e34f..2d8a01a34f 100644
--- a/hardware_interface/src/mock_components/generic_system.cpp
+++ b/hardware_interface/src/mock_components/generic_system.cpp
@@ -598,13 +598,13 @@ return_type GenericSystem::read(const rclcpp::Time & /*time*/, const rclcpp::Dur
     mirror_command_to_state(sensor_states_, sensor_mock_commands_);
   }
 
-  // do loopback on all gpio interfaces
   if (use_mock_gpio_command_interfaces_)
   {
     mirror_command_to_state(gpio_states_, gpio_mock_commands_);
   }
   else
   {
+    // do loopback on all gpio interfaces
     mirror_command_to_state(gpio_states_, gpio_commands_);
   }