diff --git a/src/backend/optimizer/path/equivclass.c b/src/backend/optimizer/path/equivclass.c
index b22b36ec0e..d78d2510ae 100644
--- a/src/backend/optimizer/path/equivclass.c
+++ b/src/backend/optimizer/path/equivclass.c
@@ -2052,6 +2052,11 @@ match_eclasses_to_foreign_key_col(PlannerInfo *root,
 			continue;
 		/* Note: it seems okay to match to "broken" eclasses here */
 
+		/* Skip over eclasses that don't have members for both rels */
+		if (!bms_is_member(var1varno, ec->ec_relids) ||
+			!bms_is_member(var2varno, ec->ec_relids))
+			continue;
+
 		foreach(lc2, ec->ec_members)
 		{
 			EquivalenceMember *em = (EquivalenceMember *) lfirst(lc2);