diff --git a/documentation/ref-manual/ref-variables.xml b/documentation/ref-manual/ref-variables.xml
index 0667c49e92..64fece31e6 100644
--- a/documentation/ref-manual/ref-variables.xml
+++ b/documentation/ref-manual/ref-variables.xml
@@ -1503,6 +1503,20 @@ recipes-graphics/xorg-font/font-alias_1.0.3.bb:PR = "${INC_PR}.3"
             </glossdef>
         </glossentry>
 
+        <glossentry id='var-KERNEL_SRC'><glossterm>KERNEL_SRC</glossterm>
+            <glossdef>
+                <para>
+                    The location of the kernel sources.
+                    This variable is set to the value of the
+                    <link linkend='var-STAGING_KERNEL_DIR'><filename>STAGING_KERNEL_DIR</filename></link>
+                    within the <filename>module.bbclass</filename> class.
+                    For information on how this variable is used, see the
+                    "<ulink url='&YOCTO_DOCS_KERNEL_DEV_URL;#incorporating-out-of-tree-modules'>Incorporating Out-of-Tree Modules</ulink>"
+                    section.
+               </para>
+            </glossdef>
+        </glossentry>
+
         <glossentry id='var-KMACHINE'><glossterm>KMACHINE</glossterm>
             <glossdef>
                 <para>