diff --git a/include/option.sh b/include/option.sh
index bfeb9eb3..3648ecd2 100755
--- a/include/option.sh
+++ b/include/option.sh
@@ -66,6 +66,11 @@ x_() {
 	[ $# -lt 1 ] || ${@} || $err "Unhandled non-zero exit: $@"; return 0
 }
 
+[ -e ".git" ] || [ -d "version" ] || printf "unknown\n" > version || \
+    $err "Cannot generate unknown version file"
+[ -e ".git" ] || [ -d "versiondate" ] || printf "1716415872\n" > versiondate || \
+    $err "Cannot generate unknown versiondate file"
+
 read -r projectname < projectname || :
 [ ! -f version ] || read -r version < version || :
 version_="${version}"