diff --git a/mysql-test/r/partition.result b/mysql-test/r/partition.result
index 03f91dc76f6..8bb895386bf 100644
--- a/mysql-test/r/partition.result
+++ b/mysql-test/r/partition.result
@@ -1074,4 +1074,12 @@ end//
 call mysqltest_1()//
 drop table t1;
 drop procedure mysqltest_1;
+create table t1 (a int, index(a))
+partition by hash(a);
+insert into t1 values (1),(2);
+select * from t1 ORDER BY a DESC;
+a
+2
+1
+drop table t1;
 End of 5.1 tests
diff --git a/mysql-test/t/partition.test b/mysql-test/t/partition.test
index 16ca22d9edb..04519800ff6 100644
--- a/mysql-test/t/partition.test
+++ b/mysql-test/t/partition.test
@@ -1252,4 +1252,13 @@ delimiter ;//
 drop table t1;
 drop procedure mysqltest_1;
 
+#
+# Bug 20583 Partitions: Crash using index_last
+#
+create table t1 (a int, index(a))
+partition by hash(a);
+insert into t1 values (1),(2);
+select * from t1 ORDER BY a DESC;
+drop table t1;
+
 --echo End of 5.1 tests
diff --git a/sql/ha_partition.cc b/sql/ha_partition.cc
index 7929257d608..c0257e08537 100644
--- a/sql/ha_partition.cc
+++ b/sql/ha_partition.cc
@@ -3400,7 +3400,8 @@ int ha_partition::common_first_last(byte *buf)
 
   if ((error= partition_scan_set_up(buf, FALSE)))
     return error;
-  if (!m_ordered_scan_ongoing)
+  if (!m_ordered_scan_ongoing &&
+      m_index_scan_type != partition_index_last)
     return handle_unordered_scan_next_partition(buf);
   return handle_ordered_index_scan(buf);
 }