diff --git a/README.md b/README.md
index c0a0e69..a6ae1bd 100644
--- a/README.md
+++ b/README.md
@@ -207,6 +207,7 @@ The following static networking parameters are only supported if `ENABLE_WIFI_DH
 |ENABLE_UBOOT|boolean|false|`true`\|`false`|Replace the default RPi 0/1/2/3 second stage bootloader (bootcode.bin) with [U-Boot bootloader](https://git.denx.de/?p=u-boot.git;a=summary). U-Boot can boot images via the network using the BOOTP/TFTP protocol. RPI4 needs tbd|
 |UBOOTSRC_DIR|string||`FullPathToUBootFolder`|Full path to a directory named `u-boot` of [U-Boot bootloader sources](https://git.denx.de/?p=u-boot.git;a=summary) that will be copied, configured, build and installed inside the chroot|
 |ENABLE_FBTURBO|boolean|false|`true`\|`false`|Install and enable the [hardware accelerated Xorg video driver](https://github.com/ssvb/xf86-video-fbturbo) `fbturbo`. Please note that this driver is currently limited to hardware accelerated window moving and scrolling|
+|ENABLE_GR_ACCEL|boolean|true|`true`\|`false`|Install and enable [one of the 3D graphics accelerators for Raspi4](https://www.raspberrypi.org/documentation/configuration/config-txt/video.md) `vc4-fkms-v3d`.  Not compatible with `fbturbo` and installed for Raspberry4 only.
 |FBTURBOSRC_DIR|string||`FullPathToFbTurboFolder`|Full path to a directory named `xf86-video-fbturbo` of [hardware accelerated Xorg video driver sources](https://github.com/ssvb/xf86-video-fbturbo) that will be copied, configured, build and installed inside the chroot|
 |ENABLE_VIDEOCORE|boolean|false|`true`\|`false`|Install and enable the [ARM side libraries for interfacing to Raspberry Pi GPU](https://github.com/raspberrypi/userland) `vcgencmd`. Please note that this driver is currently limited to hardware accelerated window moving and scrolling|
 |VIDEOCORESRC_DIR|string||`FullPathToVideoSrcFolder`|Full path to a directory named `userland` of [ARM side libraries for interfacing to Raspberry Pi GPU](https://github.com/raspberrypi/userland) that will be copied, configured, build and installed inside the chroot|
@@ -398,6 +399,6 @@ qemu-system-arm -m 2048M -M vexpress-a15 -cpu cortex-a15 -kernel kernel7.img -no
 * [Official Raspberry Pi Firmware on github](https://github.com/raspberrypi/firmware)
 * [Official Raspberry Pi Kernel on github](https://github.com/raspberrypi/linux)
 * [U-BOOT git repository](https://git.denx.de/?p=u-boot.git;a=summary)
-* [Xorg DDX driver fbturbo](https://github.com/ssvb/xf86-video-fbturbo)
+* [Xorg DDX driver #FFFFFF#FFFFFF#FFFFFF](https://github.com/ssvb/xf86-video-fbturbo)
 * [RPi3 Wireless interface firmware](https://github.com/RPi-Distro/firmware-nonfree/tree/master/brcm)
 * [Collabora RPi2 Kernel precompiled](https://repositories.collabora.co.uk/debian/)
diff --git a/rpi23-gen-image.sh b/rpi23-gen-image.sh
index 1393b8e..09e2257 100755
--- a/rpi23-gen-image.sh
+++ b/rpi23-gen-image.sh
@@ -191,7 +191,7 @@ CHROOT_SCRIPTS=${CHROOT_SCRIPTS:=""}
 ENABLE_UBOOT=${ENABLE_UBOOT:=false}
 UBOOTSRC_DIR=${UBOOTSRC_DIR:=""}
 ENABLE_FBTURBO=${ENABLE_FBTURBO:=false}
-ENABLE_GR_ACCEL=$ENABLE_GR_ACCEL:=true}
+ENABLE_GR_ACCEL=${ENABLE_GR_ACCEL:=true}
 FBTURBOSRC_DIR=${FBTURBOSRC_DIR:=""}
 ENABLE_VIDEOCORE=${ENABLE_VIDEOCORE:=false}
 VIDEOCORESRC_DIR=${VIDEOCORESRC_DIR:=""}