diff --git a/src/backend/parser/analyze.c b/src/backend/parser/analyze.c
new file mode 100644
index 1bcb875..8ed2c4b
--- a/src/backend/parser/analyze.c
+++ b/src/backend/parser/analyze.c
@@ -3291,11 +3291,28 @@ transformLockingClause(ParseState *pstat
 			foreach(rt, qry->rtable)
 			{
 				RangeTblEntry *rte = (RangeTblEntry *) lfirst(rt);
+				char	   *rtename;
 
 				++i;
 				if (!rte->inFromCl)
 					continue;
-				if (strcmp(rte->eref->aliasname, thisrel->relname) == 0)
+
+				/*
+				 * A join RTE without an alias is not visible as a relation
+				 * name and needs to be skipped (otherwise it might hide a
+				 * base relation with the same name), except if it has a USING
+				 * alias, which *is* visible.
+				 */
+				if (rte->rtekind == RTE_JOIN && rte->alias == NULL)
+				{
+					if (rte->join_using_alias == NULL)
+						continue;
+					rtename = rte->join_using_alias->aliasname;
+				}
+				else
+					rtename = rte->eref->aliasname;
+
+				if (strcmp(rtename, thisrel->relname) == 0)
 				{
 					switch (rte->rtekind)
 					{
diff --git a/src/test/regress/expected/join.out b/src/test/regress/expected/join.out
new file mode 100644
index 2538bd6..1f0df6b
--- a/src/test/regress/expected/join.out
+++ b/src/test/regress/expected/join.out
@@ -2501,6 +2501,39 @@ ERROR:  column t1.x does not exist
 LINE 1: select t1.x from t1 join t3 on (t1.a = t3.x);
                ^
 HINT:  Perhaps you meant to reference the column "t3.x".
+-- Test matching of locking clause with wrong alias
+select t1.*, t2.*, unnamed_join.* from
+  t1 join t2 on (t1.a = t2.a), t3 as unnamed_join
+  for update of unnamed_join;
+ a | b | a | b | x | y 
+---+---+---+---+---+---
+(0 rows)
+
+select foo.*, unnamed_join.* from
+  t1 join t2 using (a) as foo, t3 as unnamed_join
+  for update of unnamed_join;
+ a | x | y 
+---+---+---
+(0 rows)
+
+select foo.*, unnamed_join.* from
+  t1 join t2 using (a) as foo, t3 as unnamed_join
+  for update of foo;
+ERROR:  FOR UPDATE cannot be applied to a join
+LINE 3:   for update of foo;
+                        ^
+select bar.*, unnamed_join.* from
+  (t1 join t2 using (a) as foo) as bar, t3 as unnamed_join
+  for update of foo;
+ERROR:  relation "foo" in FOR UPDATE clause not found in FROM clause
+LINE 3:   for update of foo;
+                        ^
+select bar.*, unnamed_join.* from
+  (t1 join t2 using (a) as foo) as bar, t3 as unnamed_join
+  for update of bar;
+ERROR:  FOR UPDATE cannot be applied to a join
+LINE 3:   for update of bar;
+                        ^
 --
 -- regression test for 8.1 merge right join bug
 --
diff --git a/src/test/regress/sql/join.sql b/src/test/regress/sql/join.sql
new file mode 100644
index a27a720..b5f41c4
--- a/src/test/regress/sql/join.sql
+++ b/src/test/regress/sql/join.sql
@@ -520,6 +520,28 @@ select * from t1 left join t2 on (t1.a =
 
 select t1.x from t1 join t3 on (t1.a = t3.x);
 
+-- Test matching of locking clause with wrong alias
+
+select t1.*, t2.*, unnamed_join.* from
+  t1 join t2 on (t1.a = t2.a), t3 as unnamed_join
+  for update of unnamed_join;
+
+select foo.*, unnamed_join.* from
+  t1 join t2 using (a) as foo, t3 as unnamed_join
+  for update of unnamed_join;
+
+select foo.*, unnamed_join.* from
+  t1 join t2 using (a) as foo, t3 as unnamed_join
+  for update of foo;
+
+select bar.*, unnamed_join.* from
+  (t1 join t2 using (a) as foo) as bar, t3 as unnamed_join
+  for update of foo;
+
+select bar.*, unnamed_join.* from
+  (t1 join t2 using (a) as foo) as bar, t3 as unnamed_join
+  for update of bar;
+
 --
 -- regression test for 8.1 merge right join bug
 --