diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index 65a9b0d802..db00a593a6 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -6306,10 +6306,18 @@ plan_create_index_workers(Oid tableOid, Oid indexOid)
 	 * Currently, parallel workers can't access the leader's temporary tables.
 	 * Furthermore, any index predicate or index expressions must be parallel
 	 * safe.
+	 *
+	 * Fetch the list of expressions and predicates directly from the
+	 * catalogs.  Retrieving this information from the relcache would cause
+	 * the expressions and predicates to be flattened, losing properties that
+	 * can be important to check if parallel workers can be used.  For
+	 * example, immutable parallel-unsafe functions, that cannot be used in
+	 * parallel workers, would be changed to Const nodes, that are safe in
+	 * parallel workers.
 	 */
 	if (heap->rd_rel->relpersistence == RELPERSISTENCE_TEMP ||
-		!is_parallel_safe(root, (Node *) RelationGetIndexExpressions(index)) ||
-		!is_parallel_safe(root, (Node *) RelationGetIndexPredicate(index)))
+		!is_parallel_safe(root, (Node *) get_index_expressions(indexOid)) ||
+		!is_parallel_safe(root, (Node *) get_index_predicate(indexOid)))
 	{
 		parallel_workers = 0;
 		goto done;
diff --git a/src/backend/utils/cache/lsyscache.c b/src/backend/utils/cache/lsyscache.c
index 13f8dafa30..db6b8a36ec 100644
--- a/src/backend/utils/cache/lsyscache.c
+++ b/src/backend/utils/cache/lsyscache.c
@@ -3255,6 +3255,74 @@ get_index_column_opclass(Oid index_oid, int attno)
 	return opclass;
 }
 
+/*
+ * get_index_expressions
+ *
+ *		Given the index OID, its a List of its expressions or NIL if none.
+ */
+List *
+get_index_expressions(Oid index_oid)
+{
+	List	   *result;
+	HeapTuple	tuple;
+	Datum		exprDatum;
+	bool		isnull;
+	char	   *exprString;
+
+	tuple = SearchSysCache1(INDEXRELID, ObjectIdGetDatum(index_oid));
+	if (!HeapTupleIsValid(tuple))
+		elog(ERROR, "cache lookup failed for index %u", index_oid);
+
+	exprDatum = SysCacheGetAttr(INDEXRELID, tuple,
+								Anum_pg_index_indexprs, &isnull);
+	if (isnull)
+	{
+		ReleaseSysCache(tuple);
+		return NIL;
+	}
+
+	exprString = TextDatumGetCString(exprDatum);
+	result = (List *) stringToNode(exprString);
+	pfree(exprString);
+	ReleaseSysCache(tuple);
+
+	return result;
+}
+
+/*
+ * get_index_predicate
+ *
+ *		Given the index OID, return a List of its predicate or NIL if none.
+ */
+List *
+get_index_predicate(Oid index_oid)
+{
+	List	   *result;
+	HeapTuple	tuple;
+	Datum		predDatum;
+	bool		isnull;
+	char	   *predString;
+
+	tuple = SearchSysCache1(INDEXRELID, ObjectIdGetDatum(index_oid));
+	if (!HeapTupleIsValid(tuple))
+		elog(ERROR, "cache lookup failed for index %u", index_oid);
+
+	predDatum = SysCacheGetAttr(INDEXRELID, tuple,
+								Anum_pg_index_indpred, &isnull);
+	if (isnull)
+	{
+		ReleaseSysCache(tuple);
+		return NIL;
+	}
+
+	predString = TextDatumGetCString(predDatum);
+	result = (List *) stringToNode(predString);
+	pfree(predString);
+	ReleaseSysCache(tuple);
+
+	return result;
+}
+
 /*
  * get_index_isreplident
  *
diff --git a/src/include/utils/lsyscache.h b/src/include/utils/lsyscache.h
index 53d4a2d109..32ca83736e 100644
--- a/src/include/utils/lsyscache.h
+++ b/src/include/utils/lsyscache.h
@@ -182,6 +182,8 @@ extern char *get_namespace_name_or_temp(Oid nspid);
 extern Oid	get_range_subtype(Oid rangeOid);
 extern Oid	get_range_collation(Oid rangeOid);
 extern Oid	get_index_column_opclass(Oid index_oid, int attno);
+extern List *get_index_expressions(Oid index_oid);
+extern List *get_index_predicate(Oid index_oid);
 extern bool	get_index_isreplident(Oid index_oid);
 extern bool get_index_isvalid(Oid index_oid);
 extern bool get_index_isclustered(Oid index_oid);
diff --git a/src/test/regress/expected/btree_index.out b/src/test/regress/expected/btree_index.out
index f567117a46..8d0240f79b 100644
--- a/src/test/regress/expected/btree_index.out
+++ b/src/test/regress/expected/btree_index.out
@@ -330,3 +330,22 @@ VACUUM delete_test_table;
 -- The vacuum above should've turned the leaf page into a fast root. We just
 -- need to insert some rows to cause the fast root page to split.
 INSERT INTO delete_test_table SELECT i, 1, 2, 3 FROM generate_series(1,1000) i;
+-- Test with index expression and predicate that include a parallel unsafe
+-- function.
+CREATE FUNCTION para_unsafe_f() RETURNS int IMMUTABLE PARALLEL UNSAFE
+AS $$
+BEGIN
+    RETURN 0;
+EXCEPTION WHEN OTHERS THEN
+    RETURN 1;
+END$$ LANGUAGE plpgsql;
+CREATE TABLE btree_para_bld(i int);
+ALTER TABLE btree_para_bld SET (parallel_workers = 4);
+SET max_parallel_maintenance_workers TO 4;
+-- With parallel-unsafe expression
+CREATE INDEX ON btree_para_bld((i + para_unsafe_f()));
+-- With parallel-unsafe predicate
+CREATE INDEX ON btree_para_bld(i) WHERE i > para_unsafe_f();
+RESET max_parallel_maintenance_workers;
+DROP TABLE btree_para_bld;
+DROP FUNCTION para_unsafe_f;
diff --git a/src/test/regress/sql/btree_index.sql b/src/test/regress/sql/btree_index.sql
index 558dcae0ec..c80165c6ee 100644
--- a/src/test/regress/sql/btree_index.sql
+++ b/src/test/regress/sql/btree_index.sql
@@ -160,3 +160,25 @@ VACUUM delete_test_table;
 -- The vacuum above should've turned the leaf page into a fast root. We just
 -- need to insert some rows to cause the fast root page to split.
 INSERT INTO delete_test_table SELECT i, 1, 2, 3 FROM generate_series(1,1000) i;
+
+-- Test with index expression and predicate that include a parallel unsafe
+-- function.
+CREATE FUNCTION para_unsafe_f() RETURNS int IMMUTABLE PARALLEL UNSAFE
+AS $$
+BEGIN
+    RETURN 0;
+EXCEPTION WHEN OTHERS THEN
+    RETURN 1;
+END$$ LANGUAGE plpgsql;
+
+CREATE TABLE btree_para_bld(i int);
+ALTER TABLE btree_para_bld SET (parallel_workers = 4);
+SET max_parallel_maintenance_workers TO 4;
+-- With parallel-unsafe expression
+CREATE INDEX ON btree_para_bld((i + para_unsafe_f()));
+-- With parallel-unsafe predicate
+CREATE INDEX ON btree_para_bld(i) WHERE i > para_unsafe_f();
+
+RESET max_parallel_maintenance_workers;
+DROP TABLE btree_para_bld;
+DROP FUNCTION para_unsafe_f;