diff --git a/src/backend/statistics/mcv.c b/src/backend/statistics/mcv.c
index 35bb21c43e..0be53a89f9 100644
--- a/src/backend/statistics/mcv.c
+++ b/src/backend/statistics/mcv.c
@@ -1532,13 +1532,13 @@ pg_mcv_list_send(PG_FUNCTION_ARGS)
 /*
  * match the attribute/expression to a dimension of the statistic
  *
- * Match the attribute/expression to statistics dimension. Optionally
- * determine the collation.
+ * Returns the zero-based index of the matching statistics dimension.
+ * Optionally determines the collation.
  */
 static int
 mcv_match_expression(Node *expr, Bitmapset *keys, List *exprs, Oid *collid)
 {
-	int			idx = -1;
+	int			idx;
 
 	if (IsA(expr, Var))
 	{
@@ -1550,20 +1550,19 @@ mcv_match_expression(Node *expr, Bitmapset *keys, List *exprs, Oid *collid)
 
 		idx = bms_member_index(keys, var->varattno);
 
-		/* make sure the index is valid */
-		Assert((idx >= 0) && (idx <= bms_num_members(keys)));
+		if (idx < 0)
+			elog(ERROR, "variable not found in statistics object");
 	}
 	else
 	{
+		/* expression - lookup in stats expressions */
 		ListCell   *lc;
 
-		/* expressions are stored after the simple columns */
-		idx = bms_num_members(keys);
-
 		if (collid)
 			*collid = exprCollation(expr);
 
-		/* expression - lookup in stats expressions */
+		/* expressions are stored after the simple columns */
+		idx = bms_num_members(keys);
 		foreach(lc, exprs)
 		{
 			Node	   *stat_expr = (Node *) lfirst(lc);
@@ -1574,13 +1573,10 @@ mcv_match_expression(Node *expr, Bitmapset *keys, List *exprs, Oid *collid)
 			idx++;
 		}
 
-		/* make sure the index is valid */
-		Assert((idx >= bms_num_members(keys)) &&
-			   (idx <= bms_num_members(keys) + list_length(exprs)));
+		if (lc == NULL)
+			elog(ERROR, "expression not found in statistics object");
 	}
 
-	Assert((idx >= 0) && (idx < bms_num_members(keys) + list_length(exprs)));
-
 	return idx;
 }
 
@@ -1659,8 +1655,6 @@ mcv_get_match_bitmap(PlannerInfo *root, List *clauses,
 			/* match the attribute/expression to a dimension of the statistic */
 			idx = mcv_match_expression(clause_expr, keys, exprs, &collid);
 
-			Assert((idx >= 0) && (idx < bms_num_members(keys) + list_length(exprs)));
-
 			/*
 			 * Walk through the MCV items and evaluate the current clause. We
 			 * can skip items that were already ruled out, and terminate if
@@ -1944,7 +1938,30 @@ mcv_get_match_bitmap(PlannerInfo *root, List *clauses,
 			}
 		}
 		else
-			elog(ERROR, "unknown clause type: %d", clause->type);
+		{
+			/* Otherwise, it must be a bare boolean-returning expression */
+			int			idx;
+
+			/* match the expression to a dimension of the statistic */
+			idx = mcv_match_expression(clause, keys, exprs, NULL);
+
+			/*
+			 * Walk through the MCV items and evaluate the current clause. We
+			 * can skip items that were already ruled out, and terminate if
+			 * there are no remaining MCV items that might possibly match.
+			 */
+			for (i = 0; i < mcvlist->nitems; i++)
+			{
+				bool		match;
+				MCVItem    *item = &mcvlist->items[i];
+
+				/* "match" just means it's bool TRUE */
+				match = !item->isnull[idx] && DatumGetBool(item->values[idx]);
+
+				/* now, update the match bitmap, depending on OR/AND type */
+				matches[i] = RESULT_MERGE(matches[i], is_or, match);
+			}
+		}
 	}
 
 	return matches;
diff --git a/src/test/regress/expected/stats_ext.out b/src/test/regress/expected/stats_ext.out
index bedc703ac7..a2bc409e06 100644
--- a/src/test/regress/expected/stats_ext.out
+++ b/src/test/regress/expected/stats_ext.out
@@ -271,14 +271,23 @@ SELECT stxkind FROM pg_statistic_ext WHERE stxname = 'ab1_exprstat_3';
 CREATE STATISTICS ab1_exprstat_4 ON date_trunc('day', d) FROM ab1;
 -- date_trunc on timestamp is immutable
 CREATE STATISTICS ab1_exprstat_5 ON date_trunc('day', c) FROM ab1;
+-- check use of a boolean-returning expression
+CREATE STATISTICS ab1_exprstat_6 ON
+  (case a when 1 then true else false end), b FROM ab1;
 -- insert some data and run analyze, to test that these cases build properly
 INSERT INTO ab1
-SELECT
-    generate_series(1,10),
-    generate_series(1,10),
-    generate_series('2020-10-01'::timestamp, '2020-10-10'::timestamp, interval '1 day'),
-    generate_series('2020-10-01'::timestamptz, '2020-10-10'::timestamptz, interval '1 day');
+SELECT x / 10, x / 3,
+    '2020-10-01'::timestamp + x * interval '1 day',
+    '2020-10-01'::timestamptz + x * interval '1 day'
+FROM generate_series(1, 100) x;
 ANALYZE ab1;
+-- apply some stats
+SELECT * FROM check_estimated_rows('SELECT * FROM ab1 WHERE (case a when 1 then true else false end) AND b=2');
+ estimated | actual 
+-----------+--------
+         1 |      0
+(1 row)
+
 DROP TABLE ab1;
 -- Verify supported object types for extended statistics
 CREATE schema tststats;
diff --git a/src/test/regress/sql/stats_ext.sql b/src/test/regress/sql/stats_ext.sql
index bc229e9363..19417561bd 100644
--- a/src/test/regress/sql/stats_ext.sql
+++ b/src/test/regress/sql/stats_ext.sql
@@ -165,14 +165,21 @@ CREATE STATISTICS ab1_exprstat_4 ON date_trunc('day', d) FROM ab1;
 -- date_trunc on timestamp is immutable
 CREATE STATISTICS ab1_exprstat_5 ON date_trunc('day', c) FROM ab1;
 
+-- check use of a boolean-returning expression
+CREATE STATISTICS ab1_exprstat_6 ON
+  (case a when 1 then true else false end), b FROM ab1;
+
 -- insert some data and run analyze, to test that these cases build properly
 INSERT INTO ab1
-SELECT
-    generate_series(1,10),
-    generate_series(1,10),
-    generate_series('2020-10-01'::timestamp, '2020-10-10'::timestamp, interval '1 day'),
-    generate_series('2020-10-01'::timestamptz, '2020-10-10'::timestamptz, interval '1 day');
+SELECT x / 10, x / 3,
+    '2020-10-01'::timestamp + x * interval '1 day',
+    '2020-10-01'::timestamptz + x * interval '1 day'
+FROM generate_series(1, 100) x;
 ANALYZE ab1;
+
+-- apply some stats
+SELECT * FROM check_estimated_rows('SELECT * FROM ab1 WHERE (case a when 1 then true else false end) AND b=2');
+
 DROP TABLE ab1;
 
 -- Verify supported object types for extended statistics