diff --git a/conf/ros-distro/include/ubuntu-bionic/ros-distro-platform-preferred-versions.inc b/conf/ros-distro/include/ubuntu-bionic/ros-distro-platform-preferred-versions.inc
index 6d607f2..7290a67 100644
--- a/conf/ros-distro/include/ubuntu-bionic/ros-distro-platform-preferred-versions.inc
+++ b/conf/ros-distro/include/ubuntu-bionic/ros-distro-platform-preferred-versions.inc
@@ -7,3 +7,4 @@
 PREFERRED_VERSION_linux-raspberrypi ?= "4.4%"
 # Match kernel version of raspberrypi.
 PREFERRED_VERSION_linux-yocto ?= "4.4%"
+PREFERRED_VERSION_yajl ?= "2.1.0"
diff --git a/conf/ros-distro/include/ubuntu-bionic/ros-distro-platform-recipe-blacklist.inc b/conf/ros-distro/include/ubuntu-bionic/ros-distro-platform-recipe-blacklist.inc
index c9f2c60..6e2595e 100644
--- a/conf/ros-distro/include/ubuntu-bionic/ros-distro-platform-recipe-blacklist.inc
+++ b/conf/ros-distro/include/ubuntu-bionic/ros-distro-platform-recipe-blacklist.inc
@@ -16,4 +16,3 @@ PNBLACKLIST[linux-yocto-rt] ?= "Must specify PREFERRED_VERSION"
 PNBLACKLIST[linux-yocto-tiny] ?= "Must specify PREFERRED_VERSION"
 PNBLACKLIST[php] ?= "Must specify PREFERRED_VERSION"
 PNBLACKLIST[php-native] ?= "Must specify PREFERRED_VERSION"
-PNBLACKLIST[yajl] ?= "Must specify PREFERRED_VERSION"