diff --git a/mysql-test/r/partition.result b/mysql-test/r/partition.result
index 93684ba05e5..d13082fad55 100644
--- a/mysql-test/r/partition.result
+++ b/mysql-test/r/partition.result
@@ -1,5 +1,42 @@
 drop table if exists t1, t2;
 CREATE TABLE t1 (
+ID int(11) NOT NULL,
+`aaaa,aaaaa` tinyint(3) UNSIGNED NOT NULL DEFAULT '0',
+ddddddddd int(11) NOT NULL DEFAULT '0',
+new_field0 varchar(50),
+PRIMARY KEY(ID, `aaaa,aaaaa`, ddddddddd))
+PARTITION BY RANGE(ID)
+PARTITIONS 3
+SUBPARTITION BY LINEAR KEY(ID,`aaaa,aaaaa`)
+SUBPARTITIONS 2 (
+PARTITION p01 VALUES LESS THAN(100),
+PARTITION p11 VALUES LESS THAN(200),
+PARTITION p21 VALUES LESS THAN MAXVALUE);
+SELECT PARTITION_EXPRESSION, SUBPARTITION_EXPRESSION FROM INFORMATION_SCHEMA.PARTITIONS WHERE TABLE_NAME='t1';
+PARTITION_EXPRESSION	SUBPARTITION_EXPRESSION
+ID	`ID`,`aaaa,aaaaa`
+ID	`ID`,`aaaa,aaaaa`
+ID	`ID`,`aaaa,aaaaa`
+ID	`ID`,`aaaa,aaaaa`
+ID	`ID`,`aaaa,aaaaa`
+ID	`ID`,`aaaa,aaaaa`
+show create table t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `ID` int(11) NOT NULL,
+  `aaaa,aaaaa` tinyint(3) unsigned NOT NULL DEFAULT '0',
+  `ddddddddd` int(11) NOT NULL DEFAULT '0',
+  `new_field0` varchar(50) DEFAULT NULL,
+  PRIMARY KEY (`ID`,`aaaa,aaaaa`,`ddddddddd`)
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+/*!50100 PARTITION BY RANGE (ID)
+SUBPARTITION BY LINEAR KEY (ID,`aaaa,aaaaa`)
+SUBPARTITIONS 2
+(PARTITION p01 VALUES LESS THAN (100) ENGINE = MyISAM,
+ PARTITION p11 VALUES LESS THAN (200) ENGINE = MyISAM,
+ PARTITION p21 VALUES LESS THAN MAXVALUE ENGINE = MyISAM) */
+drop table t1;
+CREATE TABLE t1 (
 pk INT NOT NULL AUTO_INCREMENT,
 PRIMARY KEY (pk)
 )
diff --git a/mysql-test/t/partition.test b/mysql-test/t/partition.test
index 6a12e4a4d12..aaf2ee7d4bd 100644
--- a/mysql-test/t/partition.test
+++ b/mysql-test/t/partition.test
@@ -14,6 +14,29 @@
 drop table if exists t1, t2;
 --enable_warnings
 
+#
+# Bug#39338: Fieldnames in INFORMATIONSCHEMA.PARTITIONS.PARTITION_EXPRESSION
+#            become unescaped
+# NOTE: the partition expression is saved as a string, so changing from
+#       normal quotes to ansi quotes does not change the expression, only
+#       for partition by KEY.
+CREATE TABLE t1 (
+    ID int(11) NOT NULL,
+    `aaaa,aaaaa` tinyint(3) UNSIGNED NOT NULL DEFAULT '0',
+    ddddddddd int(11) NOT NULL DEFAULT '0',
+    new_field0 varchar(50),
+    PRIMARY KEY(ID, `aaaa,aaaaa`, ddddddddd))
+PARTITION BY RANGE(ID)
+PARTITIONS 3
+SUBPARTITION BY LINEAR KEY(ID,`aaaa,aaaaa`)
+SUBPARTITIONS 2 (
+    PARTITION p01 VALUES LESS THAN(100),
+    PARTITION p11 VALUES LESS THAN(200),
+    PARTITION p21 VALUES LESS THAN MAXVALUE);
+SELECT PARTITION_EXPRESSION, SUBPARTITION_EXPRESSION FROM INFORMATION_SCHEMA.PARTITIONS WHERE TABLE_NAME='t1';
+show create table t1;
+drop table t1;
+
 #
 # Bug#40954: Crash if range search and order by.
 #
diff --git a/sql/sql_show.cc b/sql/sql_show.cc
index 7b96aaf72fe..ffa888560df 100644
--- a/sql/sql_show.cc
+++ b/sql/sql_show.cc
@@ -4743,7 +4743,8 @@ static int get_schema_key_column_usage_record(THD *thd,
 
 
 #ifdef WITH_PARTITION_STORAGE_ENGINE
-static void collect_partition_expr(List<char> &field_list, String *str)
+static void collect_partition_expr(THD *thd, List<char> &field_list,
+                                   String *str)
 {
   List_iterator<char> part_it(field_list);
   ulong no_fields= field_list.elements;
@@ -4751,7 +4752,7 @@ static void collect_partition_expr(List<char> &field_list, String *str)
   str->length(0);
   while ((field_str= part_it++))
   {
-    str->append(field_str);
+    append_identifier(thd, str, field_str, strlen(field_str));
     if (--no_fields != 0)
       str->append(",");
   }
@@ -4915,7 +4916,7 @@ static int get_schema_partitions_record(THD *thd, TABLE_LIST *tables,
     }
     else if (part_info->list_of_part_fields)
     {
-      collect_partition_expr(part_info->part_field_list, &tmp_str);
+      collect_partition_expr(thd, part_info->part_field_list, &tmp_str);
       table->field[9]->store(tmp_str.ptr(), tmp_str.length(), cs);
     }
     table->field[9]->set_notnull();
@@ -4944,7 +4945,7 @@ static int get_schema_partitions_record(THD *thd, TABLE_LIST *tables,
       }
       else if (part_info->list_of_subpart_fields)
       {
-        collect_partition_expr(part_info->subpart_field_list, &tmp_str);
+        collect_partition_expr(thd, part_info->subpart_field_list, &tmp_str);
         table->field[10]->store(tmp_str.ptr(), tmp_str.length(), cs);
       }
       table->field[10]->set_notnull();