diff --git a/hardware_interface/doc/hardware_interface_types_userdoc.rst b/hardware_interface/doc/hardware_interface_types_userdoc.rst
index ae7142d751..cd1e475b20 100644
--- a/hardware_interface/doc/hardware_interface_types_userdoc.rst
+++ b/hardware_interface/doc/hardware_interface_types_userdoc.rst
@@ -86,7 +86,7 @@ They can be combined together within the different hardware component types (sys
       <gpio name="flange_analog_IOs">
         <command_interface name="analog_output1"/>
         <state_interface name="analog_output1">    <!-- Needed to know current state of the output -->
-          <param name="initial_value">3.1</param>  <!-- Optional initial value for mock_hardware or gazebo -->
+          <param name="initial_value">3.1</param>  <!-- Optional initial value for mock_hardware -->
         </state_interface>
         <state_interface name="analog_input1"/>
         <state_interface name="analog_input2"/>
diff --git a/hardware_interface/doc/mock_components_userdoc.rst b/hardware_interface/doc/mock_components_userdoc.rst
index 9e1ae299ca..c075fdeafc 100644
--- a/hardware_interface/doc/mock_components_userdoc.rst
+++ b/hardware_interface/doc/mock_components_userdoc.rst
@@ -66,4 +66,6 @@ initial_value (optional; double)
        <param name="initial_value">3.45</param>
      </state_interface>
 
-  Note: This parameter is shared with the gazebo and gazebo classic plugins.
+  Note: This parameter is shared with the gazebo and gazebo classic plugins for
+  joint interfaces. For Mock components it is also possible to set initial
+  values for gpio or sensor state interfaces.