diff --git a/package/boot/uboot-imx/Makefile b/package/boot/uboot-imx/Makefile
index 2faa48bd736..cc432697822 100644
--- a/package/boot/uboot-imx/Makefile
+++ b/package/boot/uboot-imx/Makefile
@@ -23,7 +23,7 @@ endef
 define U-Boot/apalis_imx6
   NAME:=Toradex Apalis
   UBOOT_IMAGE:=SPL u-boot.img u-boot-with-spl.imx
-  UBOOT_MAKE_FLAGS:=SPL u-boot.img u-boot-with-spl.imx
+  UBOOT_MAKE_FLAGS+=SPL u-boot.img u-boot-with-spl.imx
   BUILD_SUBTARGET:=cortexa9
   BUILD_DEVICES:=toradex_apalis
 endef
@@ -31,7 +31,7 @@ endef
 define U-Boot/mx6cuboxi
   NAME:=SolidRun Cubox-i boards
   UBOOT_IMAGE:=SPL u-boot.img
-  UBOOT_MAKE_FLAGS:=SPL u-boot.img
+  UBOOT_MAKE_FLAGS+=SPL u-boot.img
   BUILD_SUBTARGET:=cortexa9
   BUILD_DEVICES:=solidrun_cubox-i
 endef