diff --git a/src/backend/optimizer/path/equivclass.c b/src/backend/optimizer/path/equivclass.c
index a619ff91773..1d6bedb399a 100644
--- a/src/backend/optimizer/path/equivclass.c
+++ b/src/backend/optimizer/path/equivclass.c
@@ -1896,6 +1896,21 @@ create_join_clause(PlannerInfo *root,
 												  rightem->em_relids),
 										ec->ec_min_security);
 
+	/*
+	 * If either EM is a child, force the clause's clause_relids to include
+	 * the relid(s) of the child rel.  In normal cases it would already, but
+	 * not if we are considering appendrel child relations with pseudoconstant
+	 * translated variables (i.e., UNION ALL sub-selects with constant output
+	 * items).  We must do this so that join_clause_is_movable_into() will
+	 * think that the clause should be evaluated at the correct place.
+	 */
+	if (leftem->em_is_child)
+		rinfo->clause_relids = bms_add_members(rinfo->clause_relids,
+											   leftem->em_relids);
+	if (rightem->em_is_child)
+		rinfo->clause_relids = bms_add_members(rinfo->clause_relids,
+											   rightem->em_relids);
+
 	/* If it's a child clause, copy the parent's rinfo_serial */
 	if (parent_rinfo)
 		rinfo->rinfo_serial = parent_rinfo->rinfo_serial;
diff --git a/src/backend/optimizer/util/relnode.c b/src/backend/optimizer/util/relnode.c
index 0c125e42e88..e05b21c884e 100644
--- a/src/backend/optimizer/util/relnode.c
+++ b/src/backend/optimizer/util/relnode.c
@@ -1560,6 +1560,7 @@ get_baserel_parampathinfo(PlannerInfo *root, RelOptInfo *baserel,
 	ParamPathInfo *ppi;
 	Relids		joinrelids;
 	List	   *pclauses;
+	List	   *eqclauses;
 	Bitmapset  *pserials;
 	double		rows;
 	ListCell   *lc;
@@ -1595,14 +1596,25 @@ get_baserel_parampathinfo(PlannerInfo *root, RelOptInfo *baserel,
 
 	/*
 	 * Add in joinclauses generated by EquivalenceClasses, too.  (These
-	 * necessarily satisfy join_clause_is_movable_into.)
+	 * necessarily satisfy join_clause_is_movable_into; but in assert-enabled
+	 * builds, let's verify that.)
 	 */
-	pclauses = list_concat(pclauses,
-						   generate_join_implied_equalities(root,
-															joinrelids,
-															required_outer,
-															baserel,
-															NULL));
+	eqclauses = generate_join_implied_equalities(root,
+												 joinrelids,
+												 required_outer,
+												 baserel,
+												 NULL);
+#ifdef USE_ASSERT_CHECKING
+	foreach(lc, eqclauses)
+	{
+		RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc);
+
+		Assert(join_clause_is_movable_into(rinfo,
+										   baserel->relids,
+										   joinrelids));
+	}
+#endif
+	pclauses = list_concat(pclauses, eqclauses);
 
 	/* Compute set of serial numbers of the enforced clauses */
 	pserials = NULL;