diff --git a/linux-tkg-config/prepare b/linux-tkg-config/prepare
index e0d40d5..0d03e12 100644
--- a/linux-tkg-config/prepare
+++ b/linux-tkg-config/prepare
@@ -176,7 +176,11 @@ _set_kver_internal_vars() {
   _basever="${_kver_split[0]}${_kver_split[1]}"
 
   # examples: "5", "rc2", "122"
-  _sub="${_kver_split[2]}"
+  if [ -n "${_kver_split[2]}" ]; then
+    _sub="${_kver_split[2]}"
+  else
+    _sub="0"
+  fi
 
   # Append a zero to the minor if it has single digit
   [[ ${#_kver_split[1]} == "1" ]] && _kver_split[1]="0${_kver_split[1]}"