diff --git a/documentation/dev-manual/dev-manual-kernel-appendix.xml b/documentation/dev-manual/dev-manual-kernel-appendix.xml
index 996d8ae222..5caf09141b 100644
--- a/documentation/dev-manual/dev-manual-kernel-appendix.xml
+++ b/documentation/dev-manual/dev-manual-kernel-appendix.xml
@@ -577,9 +577,9 @@
                     If your host development system supports multi-core and multi-thread capabilities,
                     you can uncomment these statements and set the variables to significantly shorten
                     the full build time.
-                    As a guideline, set <filename>BB_NUMBER_THREADS</filename> to twice the number 
-                    of cores your machine supports and set <filename>PARALLEL_MAKE</filename> to one and 
-                    a half times the number of cores your machine supports.
+                    As a guideline, set both the <filename>BB_NUMBER_THREADS</filename> and the 
+                    <filename>PARALLEL_MAKE</filename> variables to twice the number 
+                    of cores your machine supports.
                 </note>
                 The following two commands <filename>source</filename> the build environment setup script
                 and build the default <filename>qemux86</filename> image.