diff --git a/Makefile b/Makefile
index 7b8efea..e8ea71c 100644
--- a/Makefile
+++ b/Makefile
@@ -1280,10 +1280,16 @@ define filechk_version.h
 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