diff --git a/include/haproxy/stats-t.h b/include/haproxy/stats-t.h
index 07eaf6d50..ca2b78d03 100644
--- a/include/haproxy/stats-t.h
+++ b/include/haproxy/stats-t.h
@@ -355,7 +355,9 @@ enum info_field {
 /* Stats fields for CSV output. For any field added here, please add the text
  * representation in the stat_fields array. Please only append at the end,
  * before the ST_F_TOTAL_FIELDS entry, and never insert anything in the middle
- * nor at the beginning.
+ * nor at the beginning.When adding an entry here, one must always add a
+ * corresponding one in stat_fields[] otherwise Lua's get_stats() will break,
+ * and "show stats" will show a null.
  */
 enum stat_field {
 	ST_F_PXNAME,
diff --git a/reg-tests/webstats/missing-stats-fields.vtc b/reg-tests/webstats/missing-stats-fields.vtc
new file mode 100644
index 000000000..c85855d5f
--- /dev/null
+++ b/reg-tests/webstats/missing-stats-fields.vtc
@@ -0,0 +1,14 @@
+varnishtest "Verifies the absence of (null) in 'show stats' header"
+
+# This can happen if a new ST_F_xxx enum is added without updating
+# stats_fields[].
+
+feature ignore_unknown_macro
+
+haproxy h1 -conf {
+} -start
+
+haproxy h1 -cli {
+    send "show stat"
+    expect !~ (null)
+}