diff --git a/samples/zephyr/hello-world/prj.conf b/samples/zephyr/hello-world/prj.conf
index cc674062..12990aac 100644
--- a/samples/zephyr/hello-world/prj.conf
+++ b/samples/zephyr/hello-world/prj.conf
@@ -7,3 +7,6 @@ CONFIG_STDOUT_CONSOLE=y
 
 # Enable Zephyr application to be booted by MCUboot
 CONFIG_BOOTLOADER_MCUBOOT=y
+
+# Use the default MCUBoot PEM key file (BOOT_SIGNATURE_KEY_FILE)
+CONFIG_MCUBOOT_SIGNATURE_KEY_FILE="bootloader/mcuboot/root-rsa-2048.pem"