--- /dev/null
+--- busybox.orig/Makefile.flags
++++ busybox/Makefile.flags
+@@ -4,6 +4,11 @@
+
+ BB_VER = $(VERSION).$(PATCHLEVEL).$(SUBLEVEL)$(EXTRAVERSION)
+ export BB_VER
++ifndef BB_EXTRA_VERSION
++BB_BT = AUTOCONF_TIMESTAMP
++else
++BB_BT = KBUILD_STR($(BB_EXTRA_VERSION))
++endif
+ SKIP_STRIP = n
+
+ # -std=gnu99 needed for [U]LLONG_MAX on some systems
+@@ -15,7 +20,7 @@
+ -include include/autoconf.h \
+ -D_GNU_SOURCE -DNDEBUG \
+ $(if $(CONFIG_LFS),-D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64) \
+- -D"BB_VER=KBUILD_STR($(BB_VER))" -DBB_BT=AUTOCONF_TIMESTAMP
++ -D"BB_VER=KBUILD_STR($(BB_VER))" -D"BB_BT=$(BB_BT)"
+
+ # flag checks are grouped together to speed the checks up a bit..
+ CFLAGS += $(call cc-option,-Wall -Wshadow -Wwrite-strings,)