diff --git a/configs/T1040RDB_SECURE_BOOT_defconfig b/configs/T1040RDB_SECURE_BOOT_defconfig
index df44b51..c15f600 100644
--- a/configs/T1040RDB_SECURE_BOOT_defconfig
+++ b/configs/T1040RDB_SECURE_BOOT_defconfig
@@ -35,4 +35,5 @@
 CONFIG_USB_STORAGE=y
 CONFIG_RSA=y
 CONFIG_SPL_RSA=y
+CONFIG_RSA_SOFTWARE_EXP=y
 CONFIG_OF_LIBFDT=y