diff --git a/boot/zephyr/external_crypto.conf b/boot/zephyr/external_crypto.conf
index 8181ad51c..c362f000a 100644
--- a/boot/zephyr/external_crypto.conf
+++ b/boot/zephyr/external_crypto.conf
@@ -18,3 +18,4 @@ CONFIG_SB_CRYPTO_CLIENT_ECDSA_SECP256R1=y
 CONFIG_SB_CRYPTO_CLIENT_SHA256=y
 CONFIG_BL_SHA256_EXT_API_REQUIRED=y
 CONFIG_BL_SECP256R1_EXT_API_REQUIRED=y
+CONFIG_EXT_API_PROVIDE_EXT_API_ATLEAST_OPTIONAL=y