diff --git a/src/backend/commands/explain.c b/src/backend/commands/explain.c
index 7ae6131676..ca6f02672b 100644
--- a/src/backend/commands/explain.c
+++ b/src/backend/commands/explain.c
@@ -2922,7 +2922,6 @@ show_incremental_sort_info(IncrementalSortState *incrsortstate,
 			 * contribute anything meaningful.
 			 */
 			fullsortGroupInfo = &incsort_info->fullsortGroupInfo;
-			prefixsortGroupInfo = &incsort_info->prefixsortGroupInfo;
 
 			/*
 			 * Since we never have any prefix groups unless we've first sorted
@@ -2930,9 +2929,11 @@ show_incremental_sort_info(IncrementalSortState *incrsortstate,
 			 * prefix group), we don't need to do anything if there were 0 full
 			 * groups.
 			 */
-			if (fullsortGroupInfo->groupCount == 0 &&
-				prefixsortGroupInfo->groupCount == 0)
+			if (fullsortGroupInfo->groupCount == 0)
+			{
+				Assert(prefixsortGroupInfo->groupCount == 0);
 				continue;
+			}
 
 			if (es->workers_state)
 				ExplainOpenWorker(n, es);
@@ -2940,6 +2941,7 @@ show_incremental_sort_info(IncrementalSortState *incrsortstate,
 			indent_first_line = es->workers_state == NULL || es->verbose;
 			show_incremental_sort_group_info(fullsortGroupInfo, "Full-sort",
 											 indent_first_line, es);
+			prefixsortGroupInfo = &incsort_info->prefixsortGroupInfo;
 			if (prefixsortGroupInfo->groupCount > 0)
 			{
 				if (es->format == EXPLAIN_FORMAT_TEXT)