diff --git a/common/Kconfig b/common/Kconfig
index 1a1951f..c759952 100644
--- a/common/Kconfig
+++ b/common/Kconfig
@@ -247,6 +247,7 @@
 config PREBOOT
 	string "preboot default value"
 	depends on USE_PREBOOT
+	default ""
 	help
 	  This is the default of "preboot" environment variable.