diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index fa7a5f8..3e7c472 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -268,6 +268,12 @@ standard_planner(Query *parse, int cursorOptions, ParamListInfo boundParams)
 	 * to assume that the same serialization level will be in effect at plan
 	 * time and execution time, so don't generate a parallel plan if we're in
 	 * serializable mode.
+	 *
+	 * Note that we don't verify here whether max_parallel_workers > 0.  If
+	 * you set max_parallel_workers_per_gather > max_parallel_workers, you
+	 * might get some plans that will never succeed in obtaining the number of
+	 * workers for which they planned.  If that bothers you, don't do it. It's
+	 * actually quite useful to do that for testing purposes, though.
 	 */
 	if ((cursorOptions & CURSOR_OPT_PARALLEL_OK) != 0 &&
 		IsUnderPostmaster &&