diff --git a/documentation/ref-manual/ref-variables.xml b/documentation/ref-manual/ref-variables.xml
index e95f35e0d7..2bd3a27a94 100644
--- a/documentation/ref-manual/ref-variables.xml
+++ b/documentation/ref-manual/ref-variables.xml
@@ -3469,6 +3469,22 @@
             </glossdef>
         </glossentry>
 
+        <glossentry id='var-IMAGE_ROOTFS_ALIGNMENT'><glossterm>IMAGE_ROOTFS_ALIGNMENT</glossterm>
+            <glossdef>
+                <para>
+                    Specifies the alignment for the output image file in
+                    Kbytes.
+                    If the size of the image is not a multiple of
+                    this value, then the size is rounded up to the nearest
+                    multiple of the value.
+                    The default value is 1 Kbyte.
+                    See
+                    <link linkend='var-IMAGE_ROOTFS_SIZE'><filename>IMAGE_ROOTFS_SIZE</filename></link>
+                    for additional information.
+                </para>
+            </glossdef>
+        </glossentry>
+
         <glossentry id='var-IMAGE_ROOTFS_EXTRA_SPACE'><glossterm>IMAGE_ROOTFS_EXTRA_SPACE</glossterm>
             <glossdef>
                 <para>