diff --git a/documentation/ref-manual/ref-variables.xml b/documentation/ref-manual/ref-variables.xml
index 5f82602f1d..1f49351f6e 100644
--- a/documentation/ref-manual/ref-variables.xml
+++ b/documentation/ref-manual/ref-variables.xml
@@ -3751,14 +3751,24 @@ recipes-graphics/xorg-font/font-alias_1.0.3.bb:PR = "${INC_PR}.3"
 
         <glossentry id='var-PARALLEL_MAKE'><glossterm>PARALLEL_MAKE</glossterm>
             <glossdef>
-                <para>Extra options that are passed to the
+                <para>
+                    Extra options that are passed to the
                     <filename>make</filename> command during the
                     <filename>do_compile</filename> task in order to specify
                     parallel compilation.
-                    This variable is usually in the form <filename>-j 4</filename>, where the number
-                    represents the maximum number of parallel threads make can run.
-                    If you development host supports multiple cores a good rule of thumb is to set
-                    this variable to twice the number of cores on the host.</para>
+                    This variable is usually in the form
+                    <filename>-j 4</filename>, where the number
+                    represents the maximum number of parallel threads make can
+                    run.
+                    If you development host supports multiple cores a good
+                    rule of thumb is to set this variable to twice the number
+                    of cores on the host.
+                    <note>
+                        Individual recipes might clear out this variable if
+                        the software being built has problems running its
+                        <filename>make</filename> process in parallel.
+                    </note>
+                </para>
             </glossdef>
         </glossentry>