diff --git a/boot/zephyr/include/config-kw.h b/boot/zephyr/include/config-kw.h
index 7cc0396..8ff31ae 100644
--- a/boot/zephyr/include/config-kw.h
+++ b/boot/zephyr/include/config-kw.h
@@ -44,6 +44,8 @@
 #define MBEDTLS_NO_DEFAULT_ENTROPY_SOURCES
 #define MBEDTLS_PLATFORM_PRINTF_ALT
 
+#define MBEDTLS_ASN1_PARSE_C
+
 #if !defined(CONFIG_ARM)
 #define MBEDTLS_HAVE_ASM
 #endif