diff --git a/documentation/poky-ref-manual/ref-variables.xml b/documentation/poky-ref-manual/ref-variables.xml
index 5b23076533..8da49b2793 100644
--- a/documentation/poky-ref-manual/ref-variables.xml
+++ b/documentation/poky-ref-manual/ref-variables.xml
@@ -670,17 +670,18 @@
Since core-image.bbclass sets IMAGE_INSTALL
to a default value using the ?= operator, using a
+= operation against IMAGE_INSTALL
- previously from the /conf/local.conf will almost always fail.
+ will result in unexpected behavior when used in
+ /conf/local.conf.
Furthermore, the same operation from with an image recipe may or may not
succeed depending on the specific situation.
In both these cases, the behavior is contrary to how most users expect
- the += append operator to work.
+ the += operator to work.
When you use this variable, it is best to use it as follows:
- IMAGE_INSTALL_append " package-name"
+ IMAGE_INSTALL_append = " package-name"
Be sure to include the space between the quotation character and the start of the
package name.