diff --git a/conf/machine/include/px30.inc b/conf/machine/include/px30.inc
index a3727fb..badcbcd 100644
--- a/conf/machine/include/px30.inc
+++ b/conf/machine/include/px30.inc
@@ -12,7 +12,7 @@ require conf/machine/include/rockchip-wic.inc
 
 KBUILD_DEFCONFIG ?= "defconfig"
 KERNEL_CLASSES = "kernel-fitimage"
-KERNEL_IMAGETYPE = "fitImage"
+KERNEL_IMAGETYPE ?= "fitImage"
 
 TFA_PLATFORM = "px30"
 TFA_BUILD_TARGET = "bl31"
diff --git a/conf/machine/include/rk3066.inc b/conf/machine/include/rk3066.inc
index fa97906..3510df2 100644
--- a/conf/machine/include/rk3066.inc
+++ b/conf/machine/include/rk3066.inc
@@ -11,4 +11,4 @@ SERIAL_CONSOLES = "115200;ttyS2"
 
 KBUILD_DEFCONFIG = "multi_v7_defconfig"
 KERNEL_FEATURES:append:rk3066 = " bsp/rockchip/remove-non-rockchip-arch-arm.scc"
-KERNEL_IMAGETYPE = "zImage"
+KERNEL_IMAGETYPE ?= "zImage"
diff --git a/conf/machine/include/rk3188.inc b/conf/machine/include/rk3188.inc
index bc96a0c..830f908 100644
--- a/conf/machine/include/rk3188.inc
+++ b/conf/machine/include/rk3188.inc
@@ -11,4 +11,4 @@ SERIAL_CONSOLES = "115200;ttyFIQ0"
 
 KBUILD_DEFCONFIG = "multi_v7_defconfig"
 KERNEL_FEATURES:append:rk3188 = " bsp/rockchip/remove-non-rockchip-arch-arm.scc"
-KERNEL_IMAGETYPE = "zImage"
+KERNEL_IMAGETYPE ?= "zImage"
diff --git a/conf/machine/include/rk3288.inc b/conf/machine/include/rk3288.inc
index b4c559d..e682c0b 100644
--- a/conf/machine/include/rk3288.inc
+++ b/conf/machine/include/rk3288.inc
@@ -11,6 +11,6 @@ SERIAL_CONSOLES = "115200;ttyS2"
 
 KBUILD_DEFCONFIG ?= "multi_v7_defconfig"
 KERNEL_FEATURES:append:rk3288 = " bsp/rockchip/remove-non-rockchip-arch-arm.scc"
-KERNEL_IMAGETYPE = "zImage"
+KERNEL_IMAGETYPE ?= "zImage"
 
 UBOOT_SUFFIX ?= "bin"
diff --git a/conf/machine/include/rk3328.inc b/conf/machine/include/rk3328.inc
index f9f8792..6be777c 100644
--- a/conf/machine/include/rk3328.inc
+++ b/conf/machine/include/rk3328.inc
@@ -13,7 +13,7 @@ require conf/machine/include/rockchip-wic.inc
 KBUILD_DEFCONFIG ?= "defconfig"
 KERNEL_FEATURES:append:rk3328 = " bsp/rockchip/remove-non-rockchip-arch-arm64.scc"
 KERNEL_CLASSES = "kernel-fitimage"
-KERNEL_IMAGETYPE = "fitImage"
+KERNEL_IMAGETYPE ?= "fitImage"
 
 TFA_PLATFORM = "rk3328"
 TFA_BUILD_TARGET = "bl31"
diff --git a/conf/machine/include/rk3399.inc b/conf/machine/include/rk3399.inc
index 88c87af..5a3f439 100644
--- a/conf/machine/include/rk3399.inc
+++ b/conf/machine/include/rk3399.inc
@@ -13,7 +13,7 @@ require conf/machine/include/rockchip-wic.inc
 KBUILD_DEFCONFIG ?= "defconfig"
 KERNEL_FEATURES:append:rk3399 = " bsp/rockchip/remove-non-rockchip-arch-arm64.scc"
 KERNEL_CLASSES = "kernel-fitimage"
-KERNEL_IMAGETYPE = "fitImage"
+KERNEL_IMAGETYPE ?= "fitImage"
 
 TFA_PLATFORM = "rk3399"
 TFA_BUILD_TARGET = "bl31"