diff --git a/heap/hp_delete.c b/heap/hp_delete.c
index 5287533ae0a..2d94418a1bf 100644
--- a/heap/hp_delete.c
+++ b/heap/hp_delete.c
@@ -80,7 +80,7 @@ int hp_rb_delete_key(HP_INFO *info, register HP_KEYDEF *keyinfo,
   custom_arg.search_flag= SEARCH_SAME;
   old_allocated= keyinfo->rb_tree.allocated;
   res= tree_delete(&keyinfo->rb_tree, info->recbuf, &custom_arg);
-  info->s->index_length+= (keyinfo->rb_tree.allocated-old_allocated);
+  info->s->index_length-= (old_allocated - keyinfo->rb_tree.allocated);
   return res;
 }
 
diff --git a/mysql-test/r/distinct.result b/mysql-test/r/distinct.result
index 3ad2b73f1d3..00436019f85 100644
--- a/mysql-test/r/distinct.result
+++ b/mysql-test/r/distinct.result
@@ -464,6 +464,46 @@ SELECT DISTINCT html,SUM(rout)/(SUM(rin)+1) as 'prod' FROM t1 GROUP BY rin;
 html	prod
 1	0.0000
 drop table t1;
+CREATE TABLE t1 (a int);
+INSERT INTO t1 VALUES (1),(2),(3),(4),(5);
+SELECT DISTINCT a, 1 FROM t1;
+a	1
+1	1
+2	1
+3	1
+4	1
+5	1
+SELECT DISTINCT 1, a FROM t1;
+1	a
+1	1
+1	2
+1	3
+1	4
+1	5
+CREATE TABLE t2 (a int, b int);
+INSERT INTO t2 VALUES (1,1),(2,2),(2,3),(2,4),(3,5);
+SELECT DISTINCT a, b, 2 FROM t2;
+a	b	2
+1	1	2
+2	2	2
+2	3	2
+2	4	2
+3	5	2
+SELECT DISTINCT 2, a, b FROM t2;
+2	a	b
+2	1	1
+2	2	2
+2	2	3
+2	2	4
+2	3	5
+SELECT DISTINCT a, 2, b FROM t2;
+a	2	b
+1	2	1
+2	2	2
+2	2	3
+2	2	4
+3	2	5
+DROP TABLE t1,t2;
 create table t1 (id int, dsc varchar(50));
 insert into t1 values (1, "line number one"), (2, "line number two"), (3, "line number three");
 select distinct id, IFNULL(dsc, '-') from t1;
diff --git a/mysql-test/t/distinct.test b/mysql-test/t/distinct.test
index 562926d160c..6483284633f 100644
--- a/mysql-test/t/distinct.test
+++ b/mysql-test/t/distinct.test
@@ -334,6 +334,22 @@ SELECT DISTINCT html,SUM(rout)/(SUM(rin)+1) as 'prod' FROM t1 GROUP BY rin;
 drop table t1;
 
 #
+# Test cases for #12625: DISTINCT for a list with constants
+#
+
+CREATE TABLE t1 (a int);
+INSERT INTO t1 VALUES (1),(2),(3),(4),(5);
+SELECT DISTINCT a, 1 FROM t1;
+SELECT DISTINCT 1, a FROM t1;
+
+CREATE TABLE t2 (a int, b int); 
+INSERT INTO t2 VALUES (1,1),(2,2),(2,3),(2,4),(3,5);
+SELECT DISTINCT a, b, 2 FROM t2;
+SELECT DISTINCT 2, a, b FROM t2;
+SELECT DISTINCT a, 2, b FROM t2;
+
+DROP TABLE t1,t2;
+
 # Bug 9784 DISTINCT IFNULL truncates data
 #
 create table t1 (id int, dsc varchar(50));
diff --git a/sql/sql_select.cc b/sql/sql_select.cc
index 901c4cbcede..893b02dab8e 100644
--- a/sql/sql_select.cc
+++ b/sql/sql_select.cc
@@ -12229,9 +12229,7 @@ create_distinct_group(THD *thd, Item **ref_pointer_array,
   li.rewind();
   while ((item=li++))
   {
-    if (item->const_item() || item->with_sum_func)
-      continue;
-    if (!item->marker)
+    if (!item->const_item() && !item->with_sum_func && !item->marker)
     {
       ORDER *ord=(ORDER*) thd->calloc(sizeof(ORDER));
       if (!ord)