diff --git a/configs/T4240QDS_SECURE_BOOT_defconfig b/configs/T4240QDS_SECURE_BOOT_defconfig
index 1372f30..3219b0c 100644
--- a/configs/T4240QDS_SECURE_BOOT_defconfig
+++ b/configs/T4240QDS_SECURE_BOOT_defconfig
@@ -31,4 +31,5 @@
 CONFIG_USB_STORAGE=y
 CONFIG_RSA=y
 CONFIG_SPL_RSA=y
+CONFIG_RSA_SOFTWARE_EXP=y
 CONFIG_OF_LIBFDT=y