diff --git a/documentation/ref-manual/ref-variables.xml b/documentation/ref-manual/ref-variables.xml
index 3fe97c6e94..a4f67fefe8 100644
--- a/documentation/ref-manual/ref-variables.xml
+++ b/documentation/ref-manual/ref-variables.xml
@@ -1319,12 +1319,11 @@ meta/conf/machine/include/<architecture>/arch-<architecture>.inc
             <glossdef>
                 <para>
                     Specifies the operating system in use on the build
-                    host (e.g. Linux).
-                    The operating system, as reported by the
-                    <filename>uname</filename> command, sets
-                    <filename>BUILD_OS</filename>.
-                    When set, the first word of the value converts to
-                    lower-case characters.
+                    host (e.g. "linux").
+                    The OpenEmbedded build system sets the value of
+                    <filename>BUILD_OS</filename> from the OS reported by
+                    the <filename>uname</filename> command - the first word,
+                    converted to lower-case characters.
                 </para>
             </glossdef>
         </glossentry>