diff --git a/build/conf/bblayers.conf b/build/conf/bblayers.conf
index 0b6c2d4..8ffe559 100644
--- a/build/conf/bblayers.conf
+++ b/build/conf/bblayers.conf
@@ -2,8 +2,8 @@
 # changes incompatibly
 POKY_BBLAYERS_CONF_VERSION = "2"
 
-BBPATH ?= "${TOPDIR}"
-BSPDIR ?= "${@os.path.abspath(os.path.dirname(d.getVar('FILE', True)) + '/../..')}"
+BBPATH = "${TOPDIR}"
+BSPDIR := "${@os.path.abspath(os.path.dirname(d.getVar('FILE', True)) + '/../..')}"
 BBFILES ?= ""
 
 BBLAYERS ?= " \