endef
 
 define filechk_timestamp.h
-       (SOURCE_DATE="$${SOURCE_DATE_EPOCH:+@$$SOURCE_DATE_EPOCH}"; \
-       LC_ALL=C date -u -d "$${SOURCE_DATE:-now}" +'#define U_BOOT_DATE "%b %d %C%y"'; \
-       LC_ALL=C date -u -d "$${SOURCE_DATE:-now}" +'#define U_BOOT_TIME "%T"'; \
-       LC_ALL=C date -u -d "$${SOURCE_DATE:-now}" +'#define U_BOOT_TZ "%z"' )
+       (if test -n "$${SOURCE_DATE_EPOCH}"; then \
+               SOURCE_DATE="@$${SOURCE_DATE_EPOCH}"; \
+               LC_ALL=C date -u -d "$${SOURCE_DATE}" +'#define U_BOOT_DATE "%b %d %C%y"'; \
+               LC_ALL=C date -u -d "$${SOURCE_DATE}" +'#define U_BOOT_TIME "%T"'; \
+               LC_ALL=C date -u -d "$${SOURCE_DATE}" +'#define U_BOOT_TZ "%z"'; \
+       else \
+               LC_ALL=C date +'#define U_BOOT_DATE "%b %d %C%y"'; \
+               LC_ALL=C date +'#define U_BOOT_TIME "%T"'; \
+               LC_ALL=C date +'#define U_BOOT_TZ "%z"'; \
+       fi)
 endef
 
 $(version_h): include/config/uboot.release FORCE