diff --git a/src/backend/utils/adt/selfuncs.c b/src/backend/utils/adt/selfuncs.c
index 52314d3aa1..2348d4a772 100644
--- a/src/backend/utils/adt/selfuncs.c
+++ b/src/backend/utils/adt/selfuncs.c
@@ -3987,11 +3987,11 @@ estimate_multivariate_ndistinct(PlannerInfo *root, RelOptInfo *rel,
 
 			attnum = ((Var *) varinfo->var)->varattno;
 
-			if (!AttrNumberIsForUserDefinedAttr(attnum))
+			if (AttrNumberIsForUserDefinedAttr(attnum) &&
+				bms_is_member(attnum, matched))
 				continue;
 
-			if (!bms_is_member(attnum, matched))
-				newlist = lappend(newlist, varinfo);
+			newlist = lappend(newlist, varinfo);
 		}
 
 		*varinfos = newlist;
diff --git a/src/test/regress/expected/stats_ext.out b/src/test/regress/expected/stats_ext.out
index 431b3fa3de..d80e6a3907 100644
--- a/src/test/regress/expected/stats_ext.out
+++ b/src/test/regress/expected/stats_ext.out
@@ -260,7 +260,7 @@ SELECT s.stxkind, d.stxdndistinct
 SELECT * FROM check_estimated_rows('SELECT COUNT(*) FROM ndistinct GROUP BY ctid, a, b');
  estimated | actual 
 -----------+--------
-        11 |   1000
+      1000 |   1000
 (1 row)
 
 -- Hash Aggregate, thanks to estimates improved by the statistic