diff --git a/include/config_fallbacks.h b/include/config_fallbacks.h
index 7d8daa2..508db56 100644
--- a/include/config_fallbacks.h
+++ b/include/config_fallbacks.h
@@ -79,6 +79,10 @@
 #define CONFIG_SYS_PROMPT	"=> "
 #endif
 
+#ifndef CONFIG_SYS_PBSIZE
+#define CONFIG_SYS_PBSIZE	(CONFIG_SYS_CBSIZE + 128)
+#endif
+
 #ifndef CONFIG_FIT_SIGNATURE
 #define CONFIG_IMAGE_FORMAT_LEGACY
 #endif