diff --git a/documentation/ref-manual/ref-variables.xml b/documentation/ref-manual/ref-variables.xml
index ad60b08af4..8d5a386184 100644
--- a/documentation/ref-manual/ref-variables.xml
+++ b/documentation/ref-manual/ref-variables.xml
@@ -4746,6 +4746,20 @@ recipes-graphics/xorg-font/font-alias_1.0.3.bb:PR = "${INC_PR}.3"
             </glossdef>
          </glossentry>
 
+         <glossentry id='var-MACHINE_ARCH'><glossterm>MACHINE_ARCH</glossterm>
+            <glossdef>
+                <para>
+                    Specifies the name of the machine-specific architecture.
+                    This variable is set automatically from
+                    <link linkend='var-MACHINE'><filename>MACHINE</filename></link>
+                    or
+                    <link linkend='var-TUNE_PKGARCH'><filename>TUNE_PKGARCH</filename></link>.
+                    You should not hand-edit the
+                    <filename>MACHINE_ARCH</filename> variable.
+                </para>
+            </glossdef>
+         </glossentry>
+
          <glossentry id='var-MACHINE_ESSENTIAL_EXTRA_RDEPENDS'><glossterm>MACHINE_ESSENTIAL_EXTRA_RDEPENDS</glossterm>
             <glossdef>
                 <para></para>