diff --git a/mysql-test/include/ctype_filesort.inc b/mysql-test/include/ctype_filesort.inc
index 2068463d4e2..b1b7f21064d 100644
--- a/mysql-test/include/ctype_filesort.inc
+++ b/mysql-test/include/ctype_filesort.inc
@@ -13,3 +13,14 @@ delete from t1;
 insert into t1 values ('a'), ('a '), ('a\t');
 select collation(a),hex(a) from t1 order by a;
 drop table t1;
+
+
+--echo #
+--echo # MDEV-5453 Assertion `src' fails in my_strnxfrm_unicode on GROUP BY MID(..) WITH ROLLUP
+--echo #
+SELECT @@collation_connection;
+CREATE TABLE t1 (i INT) ENGINE=MyISAM;
+INSERT INTO t1 VALUES (1),(2);
+SELECT * FROM t1 GROUP BY MID(CURRENT_USER,0) WITH ROLLUP;
+SELECT * FROM t1 GROUP BY MID('test',0) WITH ROLLUP; 
+DROP TABLE t1;
diff --git a/mysql-test/r/ctype_big5.result b/mysql-test/r/ctype_big5.result
index 5f734e920f4..aaf7cc9a371 100644
--- a/mysql-test/r/ctype_big5.result
+++ b/mysql-test/r/ctype_big5.result
@@ -103,6 +103,23 @@ big5_chinese_ci	6109
 big5_chinese_ci	61
 big5_chinese_ci	6120
 drop table t1;
+#
+# MDEV-5453 Assertion `src' fails in my_strnxfrm_unicode on GROUP BY MID(..) WITH ROLLUP
+#
+SELECT @@collation_connection;
+@@collation_connection
+big5_chinese_ci
+CREATE TABLE t1 (i INT) ENGINE=MyISAM;
+INSERT INTO t1 VALUES (1),(2);
+SELECT * FROM t1 GROUP BY MID(CURRENT_USER,0) WITH ROLLUP;
+i
+1
+1
+SELECT * FROM t1 GROUP BY MID('test',0) WITH ROLLUP;
+i
+1
+1
+DROP TABLE t1;
 create table t1 engine=innodb select repeat('a',50) as c1;
 alter table t1 add index(c1(5));
 insert into t1 values ('abcdefg'),('abcde100'),('abcde110'),('abcde111');
@@ -250,6 +267,23 @@ big5_bin	6109
 big5_bin	61
 big5_bin	6120
 drop table t1;
+#
+# MDEV-5453 Assertion `src' fails in my_strnxfrm_unicode on GROUP BY MID(..) WITH ROLLUP
+#
+SELECT @@collation_connection;
+@@collation_connection
+big5_bin
+CREATE TABLE t1 (i INT) ENGINE=MyISAM;
+INSERT INTO t1 VALUES (1),(2);
+SELECT * FROM t1 GROUP BY MID(CURRENT_USER,0) WITH ROLLUP;
+i
+1
+1
+SELECT * FROM t1 GROUP BY MID('test',0) WITH ROLLUP;
+i
+1
+1
+DROP TABLE t1;
 create table t1 engine=innodb select repeat('a',50) as c1;
 alter table t1 add index(c1(5));
 insert into t1 values ('abcdefg'),('abcde100'),('abcde110'),('abcde111');
diff --git a/mysql-test/r/ctype_cp1250_ch.result b/mysql-test/r/ctype_cp1250_ch.result
index b5e4da336cd..96e81f04613 100644
--- a/mysql-test/r/ctype_cp1250_ch.result
+++ b/mysql-test/r/ctype_cp1250_ch.result
@@ -263,6 +263,23 @@ cp1250_czech_cs	61
 cp1250_czech_cs	6109
 cp1250_czech_cs	6120
 drop table t1;
+#
+# MDEV-5453 Assertion `src' fails in my_strnxfrm_unicode on GROUP BY MID(..) WITH ROLLUP
+#
+SELECT @@collation_connection;
+@@collation_connection
+cp1250_czech_cs
+CREATE TABLE t1 (i INT) ENGINE=MyISAM;
+INSERT INTO t1 VALUES (1),(2);
+SELECT * FROM t1 GROUP BY MID(CURRENT_USER,0) WITH ROLLUP;
+i
+1
+1
+SELECT * FROM t1 GROUP BY MID('test',0) WITH ROLLUP;
+i
+1
+1
+DROP TABLE t1;
 set global LC_MESSAGES=convert((@@global.log_bin_trust_function_creators) 
 using cp1250);
 ERROR HY000: Unknown locale: '1'
diff --git a/mysql-test/r/ctype_eucjpms.result b/mysql-test/r/ctype_eucjpms.result
index 70cebf3f80d..8b56e5ceb24 100644
--- a/mysql-test/r/ctype_eucjpms.result
+++ b/mysql-test/r/ctype_eucjpms.result
@@ -9809,6 +9809,23 @@ eucjpms_japanese_ci	6109
 eucjpms_japanese_ci	61
 eucjpms_japanese_ci	6120
 drop table t1;
+#
+# MDEV-5453 Assertion `src' fails in my_strnxfrm_unicode on GROUP BY MID(..) WITH ROLLUP
+#
+SELECT @@collation_connection;
+@@collation_connection
+eucjpms_japanese_ci
+CREATE TABLE t1 (i INT) ENGINE=MyISAM;
+INSERT INTO t1 VALUES (1),(2);
+SELECT * FROM t1 GROUP BY MID(CURRENT_USER,0) WITH ROLLUP;
+i
+1
+1
+SELECT * FROM t1 GROUP BY MID('test',0) WITH ROLLUP;
+i
+1
+1
+DROP TABLE t1;
 CREATE TABLE t1 AS
 SELECT 10 AS a, REPEAT('a',20) AS b, REPEAT('a',8) AS c, REPEAT('a',8) AS d;
 ALTER TABLE t1 ADD PRIMARY KEY(a), ADD KEY(b);
@@ -9836,6 +9853,23 @@ eucjpms_bin	6109
 eucjpms_bin	61
 eucjpms_bin	6120
 drop table t1;
+#
+# MDEV-5453 Assertion `src' fails in my_strnxfrm_unicode on GROUP BY MID(..) WITH ROLLUP
+#
+SELECT @@collation_connection;
+@@collation_connection
+eucjpms_bin
+CREATE TABLE t1 (i INT) ENGINE=MyISAM;
+INSERT INTO t1 VALUES (1),(2);
+SELECT * FROM t1 GROUP BY MID(CURRENT_USER,0) WITH ROLLUP;
+i
+1
+1
+SELECT * FROM t1 GROUP BY MID('test',0) WITH ROLLUP;
+i
+1
+1
+DROP TABLE t1;
 CREATE TABLE t1 AS
 SELECT 10 AS a, REPEAT('a',20) AS b, REPEAT('a',8) AS c, REPEAT('a',8) AS d;
 ALTER TABLE t1 ADD PRIMARY KEY(a), ADD KEY(b);
diff --git a/mysql-test/r/ctype_euckr.result b/mysql-test/r/ctype_euckr.result
index 4b395359373..525f14946d7 100644
--- a/mysql-test/r/ctype_euckr.result
+++ b/mysql-test/r/ctype_euckr.result
@@ -103,6 +103,23 @@ euckr_korean_ci	6109
 euckr_korean_ci	61
 euckr_korean_ci	6120
 drop table t1;
+#
+# MDEV-5453 Assertion `src' fails in my_strnxfrm_unicode on GROUP BY MID(..) WITH ROLLUP
+#
+SELECT @@collation_connection;
+@@collation_connection
+euckr_korean_ci
+CREATE TABLE t1 (i INT) ENGINE=MyISAM;
+INSERT INTO t1 VALUES (1),(2);
+SELECT * FROM t1 GROUP BY MID(CURRENT_USER,0) WITH ROLLUP;
+i
+1
+1
+SELECT * FROM t1 GROUP BY MID('test',0) WITH ROLLUP;
+i
+1
+1
+DROP TABLE t1;
 create table t1 engine=innodb select repeat('a',50) as c1;
 alter table t1 add index(c1(5));
 insert into t1 values ('abcdefg'),('abcde100'),('abcde110'),('abcde111');
@@ -170,6 +187,23 @@ euckr_bin	6109
 euckr_bin	61
 euckr_bin	6120
 drop table t1;
+#
+# MDEV-5453 Assertion `src' fails in my_strnxfrm_unicode on GROUP BY MID(..) WITH ROLLUP
+#
+SELECT @@collation_connection;
+@@collation_connection
+euckr_bin
+CREATE TABLE t1 (i INT) ENGINE=MyISAM;
+INSERT INTO t1 VALUES (1),(2);
+SELECT * FROM t1 GROUP BY MID(CURRENT_USER,0) WITH ROLLUP;
+i
+1
+1
+SELECT * FROM t1 GROUP BY MID('test',0) WITH ROLLUP;
+i
+1
+1
+DROP TABLE t1;
 create table t1 engine=innodb select repeat('a',50) as c1;
 alter table t1 add index(c1(5));
 insert into t1 values ('abcdefg'),('abcde100'),('abcde110'),('abcde111');
diff --git a/mysql-test/r/ctype_gb2312.result b/mysql-test/r/ctype_gb2312.result
index daefcc8e11d..a625c0f08d3 100644
--- a/mysql-test/r/ctype_gb2312.result
+++ b/mysql-test/r/ctype_gb2312.result
@@ -103,6 +103,23 @@ gb2312_chinese_ci	6109
 gb2312_chinese_ci	61
 gb2312_chinese_ci	6120
 drop table t1;
+#
+# MDEV-5453 Assertion `src' fails in my_strnxfrm_unicode on GROUP BY MID(..) WITH ROLLUP
+#
+SELECT @@collation_connection;
+@@collation_connection
+gb2312_chinese_ci
+CREATE TABLE t1 (i INT) ENGINE=MyISAM;
+INSERT INTO t1 VALUES (1),(2);
+SELECT * FROM t1 GROUP BY MID(CURRENT_USER,0) WITH ROLLUP;
+i
+1
+1
+SELECT * FROM t1 GROUP BY MID('test',0) WITH ROLLUP;
+i
+1
+1
+DROP TABLE t1;
 create table t1 engine=innodb select repeat('a',50) as c1;
 alter table t1 add index(c1(5));
 insert into t1 values ('abcdefg'),('abcde100'),('abcde110'),('abcde111');
@@ -251,6 +268,23 @@ gb2312_bin	6109
 gb2312_bin	61
 gb2312_bin	6120
 drop table t1;
+#
+# MDEV-5453 Assertion `src' fails in my_strnxfrm_unicode on GROUP BY MID(..) WITH ROLLUP
+#
+SELECT @@collation_connection;
+@@collation_connection
+gb2312_bin
+CREATE TABLE t1 (i INT) ENGINE=MyISAM;
+INSERT INTO t1 VALUES (1),(2);
+SELECT * FROM t1 GROUP BY MID(CURRENT_USER,0) WITH ROLLUP;
+i
+1
+1
+SELECT * FROM t1 GROUP BY MID('test',0) WITH ROLLUP;
+i
+1
+1
+DROP TABLE t1;
 create table t1 engine=innodb select repeat('a',50) as c1;
 alter table t1 add index(c1(5));
 insert into t1 values ('abcdefg'),('abcde100'),('abcde110'),('abcde111');
diff --git a/mysql-test/r/ctype_gbk.result b/mysql-test/r/ctype_gbk.result
index 801436ac326..31d61a7e98a 100644
--- a/mysql-test/r/ctype_gbk.result
+++ b/mysql-test/r/ctype_gbk.result
@@ -103,6 +103,23 @@ gbk_chinese_ci	6109
 gbk_chinese_ci	61
 gbk_chinese_ci	6120
 drop table t1;
+#
+# MDEV-5453 Assertion `src' fails in my_strnxfrm_unicode on GROUP BY MID(..) WITH ROLLUP
+#
+SELECT @@collation_connection;
+@@collation_connection
+gbk_chinese_ci
+CREATE TABLE t1 (i INT) ENGINE=MyISAM;
+INSERT INTO t1 VALUES (1),(2);
+SELECT * FROM t1 GROUP BY MID(CURRENT_USER,0) WITH ROLLUP;
+i
+1
+1
+SELECT * FROM t1 GROUP BY MID('test',0) WITH ROLLUP;
+i
+1
+1
+DROP TABLE t1;
 create table t1 engine=innodb select repeat('a',50) as c1;
 alter table t1 add index(c1(5));
 insert into t1 values ('abcdefg'),('abcde100'),('abcde110'),('abcde111');
@@ -251,6 +268,23 @@ gbk_bin	6109
 gbk_bin	61
 gbk_bin	6120
 drop table t1;
+#
+# MDEV-5453 Assertion `src' fails in my_strnxfrm_unicode on GROUP BY MID(..) WITH ROLLUP
+#
+SELECT @@collation_connection;
+@@collation_connection
+gbk_bin
+CREATE TABLE t1 (i INT) ENGINE=MyISAM;
+INSERT INTO t1 VALUES (1),(2);
+SELECT * FROM t1 GROUP BY MID(CURRENT_USER,0) WITH ROLLUP;
+i
+1
+1
+SELECT * FROM t1 GROUP BY MID('test',0) WITH ROLLUP;
+i
+1
+1
+DROP TABLE t1;
 create table t1 engine=innodb select repeat('a',50) as c1;
 alter table t1 add index(c1(5));
 insert into t1 values ('abcdefg'),('abcde100'),('abcde110'),('abcde111');
diff --git a/mysql-test/r/ctype_latin1.result b/mysql-test/r/ctype_latin1.result
index 48ab72a4b8b..630288ebcb7 100644
--- a/mysql-test/r/ctype_latin1.result
+++ b/mysql-test/r/ctype_latin1.result
@@ -318,6 +318,23 @@ latin1_swedish_ci	6109
 latin1_swedish_ci	61
 latin1_swedish_ci	6120
 drop table t1;
+#
+# MDEV-5453 Assertion `src' fails in my_strnxfrm_unicode on GROUP BY MID(..) WITH ROLLUP
+#
+SELECT @@collation_connection;
+@@collation_connection
+latin1_swedish_ci
+CREATE TABLE t1 (i INT) ENGINE=MyISAM;
+INSERT INTO t1 VALUES (1),(2);
+SELECT * FROM t1 GROUP BY MID(CURRENT_USER,0) WITH ROLLUP;
+i
+1
+1
+SELECT * FROM t1 GROUP BY MID('test',0) WITH ROLLUP;
+i
+1
+1
+DROP TABLE t1;
 select @@collation_connection;
 @@collation_connection
 latin1_swedish_ci
@@ -365,6 +382,23 @@ latin1_bin	6109
 latin1_bin	61
 latin1_bin	6120
 drop table t1;
+#
+# MDEV-5453 Assertion `src' fails in my_strnxfrm_unicode on GROUP BY MID(..) WITH ROLLUP
+#
+SELECT @@collation_connection;
+@@collation_connection
+latin1_bin
+CREATE TABLE t1 (i INT) ENGINE=MyISAM;
+INSERT INTO t1 VALUES (1),(2);
+SELECT * FROM t1 GROUP BY MID(CURRENT_USER,0) WITH ROLLUP;
+i
+1
+1
+SELECT * FROM t1 GROUP BY MID('test',0) WITH ROLLUP;
+i
+1
+1
+DROP TABLE t1;
 select @@collation_connection;
 @@collation_connection
 latin1_bin
diff --git a/mysql-test/r/ctype_latin1_de.result b/mysql-test/r/ctype_latin1_de.result
index 54cc1a6e025..ceb0a65304b 100644
--- a/mysql-test/r/ctype_latin1_de.result
+++ b/mysql-test/r/ctype_latin1_de.result
@@ -326,6 +326,23 @@ latin1_german2_ci	6109
 latin1_german2_ci	61
 latin1_german2_ci	6120
 drop table t1;
+#
+# MDEV-5453 Assertion `src' fails in my_strnxfrm_unicode on GROUP BY MID(..) WITH ROLLUP
+#
+SELECT @@collation_connection;
+@@collation_connection
+latin1_german2_ci
+CREATE TABLE t1 (i INT) ENGINE=MyISAM;
+INSERT INTO t1 VALUES (1),(2);
+SELECT * FROM t1 GROUP BY MID(CURRENT_USER,0) WITH ROLLUP;
+i
+1
+1
+SELECT * FROM t1 GROUP BY MID('test',0) WITH ROLLUP;
+i
+1
+1
+DROP TABLE t1;
 "BEGIN ctype_german.inc"
 drop table if exists t1;
 create table t1 as select repeat(' ', 64) as s1;
diff --git a/mysql-test/r/ctype_sjis.result b/mysql-test/r/ctype_sjis.result
index 679b5208cf5..994a16261f5 100644
--- a/mysql-test/r/ctype_sjis.result
+++ b/mysql-test/r/ctype_sjis.result
@@ -81,6 +81,23 @@ sjis_japanese_ci	6109
 sjis_japanese_ci	61
 sjis_japanese_ci	6120
 drop table t1;
+#
+# MDEV-5453 Assertion `src' fails in my_strnxfrm_unicode on GROUP BY MID(..) WITH ROLLUP
+#
+SELECT @@collation_connection;
+@@collation_connection
+sjis_japanese_ci
+CREATE TABLE t1 (i INT) ENGINE=MyISAM;
+INSERT INTO t1 VALUES (1),(2);
+SELECT * FROM t1 GROUP BY MID(CURRENT_USER,0) WITH ROLLUP;
+i
+1
+1
+SELECT * FROM t1 GROUP BY MID('test',0) WITH ROLLUP;
+i
+1
+1
+DROP TABLE t1;
 create table t1 engine=innodb select repeat('a',50) as c1;
 alter table t1 add index(c1(5));
 insert into t1 values ('abcdefg'),('abcde100'),('abcde110'),('abcde111');
@@ -167,6 +184,23 @@ sjis_bin	6109
 sjis_bin	61
 sjis_bin	6120
 drop table t1;
+#
+# MDEV-5453 Assertion `src' fails in my_strnxfrm_unicode on GROUP BY MID(..) WITH ROLLUP
+#
+SELECT @@collation_connection;
+@@collation_connection
+sjis_bin
+CREATE TABLE t1 (i INT) ENGINE=MyISAM;
+INSERT INTO t1 VALUES (1),(2);
+SELECT * FROM t1 GROUP BY MID(CURRENT_USER,0) WITH ROLLUP;
+i
+1
+1
+SELECT * FROM t1 GROUP BY MID('test',0) WITH ROLLUP;
+i
+1
+1
+DROP TABLE t1;
 create table t1 engine=innodb select repeat('a',50) as c1;
 alter table t1 add index(c1(5));
 insert into t1 values ('abcdefg'),('abcde100'),('abcde110'),('abcde111');
diff --git a/mysql-test/r/ctype_tis620.result b/mysql-test/r/ctype_tis620.result
index c97d0507463..70f58f91d38 100644
--- a/mysql-test/r/ctype_tis620.result
+++ b/mysql-test/r/ctype_tis620.result
@@ -2947,6 +2947,23 @@ tis620_thai_ci	6109
 tis620_thai_ci	61
 tis620_thai_ci	6120
 drop table t1;
+#
+# MDEV-5453 Assertion `src' fails in my_strnxfrm_unicode on GROUP BY MID(..) WITH ROLLUP
+#
+SELECT @@collation_connection;
+@@collation_connection
+tis620_thai_ci
+CREATE TABLE t1 (i INT) ENGINE=MyISAM;
+INSERT INTO t1 VALUES (1),(2);
+SELECT * FROM t1 GROUP BY MID(CURRENT_USER,0) WITH ROLLUP;
+i
+1
+1
+SELECT * FROM t1 GROUP BY MID('test',0) WITH ROLLUP;
+i
+1
+1
+DROP TABLE t1;
 select @@collation_connection;
 @@collation_connection
 tis620_thai_ci
@@ -3057,6 +3074,23 @@ tis620_bin	6109
 tis620_bin	61
 tis620_bin	6120
 drop table t1;
+#
+# MDEV-5453 Assertion `src' fails in my_strnxfrm_unicode on GROUP BY MID(..) WITH ROLLUP
+#
+SELECT @@collation_connection;
+@@collation_connection
+tis620_bin
+CREATE TABLE t1 (i INT) ENGINE=MyISAM;
+INSERT INTO t1 VALUES (1),(2);
+SELECT * FROM t1 GROUP BY MID(CURRENT_USER,0) WITH ROLLUP;
+i
+1
+1
+SELECT * FROM t1 GROUP BY MID('test',0) WITH ROLLUP;
+i
+1
+1
+DROP TABLE t1;
 select @@collation_connection;
 @@collation_connection
 tis620_bin
diff --git a/mysql-test/r/ctype_uca.result b/mysql-test/r/ctype_uca.result
index d6407301b90..c92592cacd3 100644
--- a/mysql-test/r/ctype_uca.result
+++ b/mysql-test/r/ctype_uca.result
@@ -5883,6 +5883,23 @@ utf8_unicode_ci	6109
 utf8_unicode_ci	61
 utf8_unicode_ci	6120
 drop table t1;
+#
+# MDEV-5453 Assertion `src' fails in my_strnxfrm_unicode on GROUP BY MID(..) WITH ROLLUP
+#
+SELECT @@collation_connection;
+@@collation_connection
+utf8_unicode_ci
+CREATE TABLE t1 (i INT) ENGINE=MyISAM;
+INSERT INTO t1 VALUES (1),(2);
+SELECT * FROM t1 GROUP BY MID(CURRENT_USER,0) WITH ROLLUP;
+i
+1
+1
+SELECT * FROM t1 GROUP BY MID('test',0) WITH ROLLUP;
+i
+1
+1
+DROP TABLE t1;
 select @@collation_connection;
 @@collation_connection
 utf8_unicode_ci
diff --git a/mysql-test/r/ctype_ucs.result b/mysql-test/r/ctype_ucs.result
index ee69544b274..5ce58fd7617 100644
--- a/mysql-test/r/ctype_ucs.result
+++ b/mysql-test/r/ctype_ucs.result
@@ -744,6 +744,23 @@ ucs2_general_ci	00610009
 ucs2_general_ci	0061
 ucs2_general_ci	00610020
 drop table t1;
+#
+# MDEV-5453 Assertion `src' fails in my_strnxfrm_unicode on GROUP BY MID(..) WITH ROLLUP
+#
+SELECT @@collation_connection;
+@@collation_connection
+ucs2_general_ci
+CREATE TABLE t1 (i INT) ENGINE=MyISAM;
+INSERT INTO t1 VALUES (1),(2);
+SELECT * FROM t1 GROUP BY MID(CURRENT_USER,0) WITH ROLLUP;
+i
+1
+1
+SELECT * FROM t1 GROUP BY MID('test',0) WITH ROLLUP;
+i
+1
+1
+DROP TABLE t1;
 select @@collation_connection;
 @@collation_connection
 ucs2_general_ci
@@ -925,6 +942,23 @@ ucs2_bin	00610009
 ucs2_bin	0061
 ucs2_bin	00610020
 drop table t1;
+#
+# MDEV-5453 Assertion `src' fails in my_strnxfrm_unicode on GROUP BY MID(..) WITH ROLLUP
+#
+SELECT @@collation_connection;
+@@collation_connection
+ucs2_bin
+CREATE TABLE t1 (i INT) ENGINE=MyISAM;
+INSERT INTO t1 VALUES (1),(2);
+SELECT * FROM t1 GROUP BY MID(CURRENT_USER,0) WITH ROLLUP;
+i
+1
+1
+SELECT * FROM t1 GROUP BY MID('test',0) WITH ROLLUP;
+i
+1
+1
+DROP TABLE t1;
 select @@collation_connection;
 @@collation_connection
 ucs2_bin
diff --git a/mysql-test/r/ctype_ujis.result b/mysql-test/r/ctype_ujis.result
index 4391029b765..aace88419fb 100644
--- a/mysql-test/r/ctype_ujis.result
+++ b/mysql-test/r/ctype_ujis.result
@@ -2217,6 +2217,23 @@ ujis_japanese_ci	6109
 ujis_japanese_ci	61
 ujis_japanese_ci	6120
 drop table t1;
+#
+# MDEV-5453 Assertion `src' fails in my_strnxfrm_unicode on GROUP BY MID(..) WITH ROLLUP
+#
+SELECT @@collation_connection;
+@@collation_connection
+ujis_japanese_ci
+CREATE TABLE t1 (i INT) ENGINE=MyISAM;
+INSERT INTO t1 VALUES (1),(2);
+SELECT * FROM t1 GROUP BY MID(CURRENT_USER,0) WITH ROLLUP;
+i
+1
+1
+SELECT * FROM t1 GROUP BY MID('test',0) WITH ROLLUP;
+i
+1
+1
+DROP TABLE t1;
 create table t1 engine=innodb select repeat('a',50) as c1;
 alter table t1 add index(c1(5));
 insert into t1 values ('abcdefg'),('abcde100'),('abcde110'),('abcde111');
@@ -2284,6 +2301,23 @@ ujis_bin	6109
 ujis_bin	61
 ujis_bin	6120
 drop table t1;
+#
+# MDEV-5453 Assertion `src' fails in my_strnxfrm_unicode on GROUP BY MID(..) WITH ROLLUP
+#
+SELECT @@collation_connection;
+@@collation_connection
+ujis_bin
+CREATE TABLE t1 (i INT) ENGINE=MyISAM;
+INSERT INTO t1 VALUES (1),(2);
+SELECT * FROM t1 GROUP BY MID(CURRENT_USER,0) WITH ROLLUP;
+i
+1
+1
+SELECT * FROM t1 GROUP BY MID('test',0) WITH ROLLUP;
+i
+1
+1
+DROP TABLE t1;
 create table t1 engine=innodb select repeat('a',50) as c1;
 alter table t1 add index(c1(5));
 insert into t1 values ('abcdefg'),('abcde100'),('abcde110'),('abcde111');
diff --git a/mysql-test/r/ctype_utf16.result b/mysql-test/r/ctype_utf16.result
index 29abffa0d52..6925da6b206 100644
--- a/mysql-test/r/ctype_utf16.result
+++ b/mysql-test/r/ctype_utf16.result
@@ -583,6 +583,23 @@ utf16_general_ci	00610009
 utf16_general_ci	0061
 utf16_general_ci	00610020
 drop table t1;
+#
+# MDEV-5453 Assertion `src' fails in my_strnxfrm_unicode on GROUP BY MID(..) WITH ROLLUP
+#
+SELECT @@collation_connection;
+@@collation_connection
+utf16_general_ci
+CREATE TABLE t1 (i INT) ENGINE=MyISAM;
+INSERT INTO t1 VALUES (1),(2);
+SELECT * FROM t1 GROUP BY MID(CURRENT_USER,0) WITH ROLLUP;
+i
+1
+1
+SELECT * FROM t1 GROUP BY MID('test',0) WITH ROLLUP;
+i
+1
+1
+DROP TABLE t1;
 select @@collation_connection;
 @@collation_connection
 utf16_general_ci
@@ -613,6 +630,23 @@ utf16_bin	0061
 utf16_bin	00610020
 drop table t1;
 #
+# MDEV-5453 Assertion `src' fails in my_strnxfrm_unicode on GROUP BY MID(..) WITH ROLLUP
+#
+SELECT @@collation_connection;
+@@collation_connection
+utf16_bin
+CREATE TABLE t1 (i INT) ENGINE=MyISAM;
+INSERT INTO t1 VALUES (1),(2);
+SELECT * FROM t1 GROUP BY MID(CURRENT_USER,0) WITH ROLLUP;
+i
+1
+1
+SELECT * FROM t1 GROUP BY MID('test',0) WITH ROLLUP;
+i
+1
+1
+DROP TABLE t1;
+#
 # Bug#55980 Character sets: supplementary character _bin ordering is wrong
 #
 CREATE TABLE t1 AS SELECT REPEAT('a',1) AS a LIMIT 0;
diff --git a/mysql-test/r/ctype_utf16_uca.result b/mysql-test/r/ctype_utf16_uca.result
index d5d0c29ff11..edb620df974 100644
--- a/mysql-test/r/ctype_utf16_uca.result
+++ b/mysql-test/r/ctype_utf16_uca.result
@@ -2857,6 +2857,23 @@ utf16_unicode_ci	00610009
 utf16_unicode_ci	0061
 utf16_unicode_ci	00610020
 drop table t1;
+#
+# MDEV-5453 Assertion `src' fails in my_strnxfrm_unicode on GROUP BY MID(..) WITH ROLLUP
+#
+SELECT @@collation_connection;
+@@collation_connection
+utf16_unicode_ci
+CREATE TABLE t1 (i INT) ENGINE=MyISAM;
+INSERT INTO t1 VALUES (1),(2);
+SELECT * FROM t1 GROUP BY MID(CURRENT_USER,0) WITH ROLLUP;
+i
+1
+1
+SELECT * FROM t1 GROUP BY MID('test',0) WITH ROLLUP;
+i
+1
+1
+DROP TABLE t1;
 select @@collation_connection;
 @@collation_connection
 utf16_unicode_ci
diff --git a/mysql-test/r/ctype_utf16le.result b/mysql-test/r/ctype_utf16le.result
index 2d032b925ca..8f63dda2adc 100644
--- a/mysql-test/r/ctype_utf16le.result
+++ b/mysql-test/r/ctype_utf16le.result
@@ -627,6 +627,23 @@ utf16le_general_ci	61000900
 utf16le_general_ci	6100
 utf16le_general_ci	61002000
 drop table t1;
+#
+# MDEV-5453 Assertion `src' fails in my_strnxfrm_unicode on GROUP BY MID(..) WITH ROLLUP
+#
+SELECT @@collation_connection;
+@@collation_connection
+utf16le_general_ci
+CREATE TABLE t1 (i INT) ENGINE=MyISAM;
+INSERT INTO t1 VALUES (1),(2);
+SELECT * FROM t1 GROUP BY MID(CURRENT_USER,0) WITH ROLLUP;
+i
+1
+1
+SELECT * FROM t1 GROUP BY MID('test',0) WITH ROLLUP;
+i
+1
+1
+DROP TABLE t1;
 select @@collation_connection;
 @@collation_connection
 utf16le_general_ci
@@ -656,6 +673,23 @@ utf16le_bin	6100
 utf16le_bin	61002000
 drop table t1;
 #
+# MDEV-5453 Assertion `src' fails in my_strnxfrm_unicode on GROUP BY MID(..) WITH ROLLUP
+#
+SELECT @@collation_connection;
+@@collation_connection
+utf16le_bin
+CREATE TABLE t1 (i INT) ENGINE=MyISAM;
+INSERT INTO t1 VALUES (1),(2);
+SELECT * FROM t1 GROUP BY MID(CURRENT_USER,0) WITH ROLLUP;
+i
+1
+1
+SELECT * FROM t1 GROUP BY MID('test',0) WITH ROLLUP;
+i
+1
+1
+DROP TABLE t1;
+#
 # Bug#55980 Character sets: supplementary character _bin ordering is wrong
 #
 CREATE TABLE t1 AS SELECT REPEAT('a',1) AS a LIMIT 0;
diff --git a/mysql-test/r/ctype_utf32.result b/mysql-test/r/ctype_utf32.result
index c72ae5ef90f..e0bede76fb7 100644
--- a/mysql-test/r/ctype_utf32.result
+++ b/mysql-test/r/ctype_utf32.result
@@ -582,6 +582,23 @@ utf32_general_ci	0000006100000009
 utf32_general_ci	00000061
 utf32_general_ci	0000006100000020
 drop table t1;
+#
+# MDEV-5453 Assertion `src' fails in my_strnxfrm_unicode on GROUP BY MID(..) WITH ROLLUP
+#
+SELECT @@collation_connection;
+@@collation_connection
+utf32_general_ci
+CREATE TABLE t1 (i INT) ENGINE=MyISAM;
+INSERT INTO t1 VALUES (1),(2);
+SELECT * FROM t1 GROUP BY MID(CURRENT_USER,0) WITH ROLLUP;
+i
+1
+1
+SELECT * FROM t1 GROUP BY MID('test',0) WITH ROLLUP;
+i
+1
+1
+DROP TABLE t1;
 select @@collation_connection;
 @@collation_connection
 utf32_general_ci
@@ -612,6 +629,23 @@ utf32_bin	00000061
 utf32_bin	0000006100000020
 drop table t1;
 #
+# MDEV-5453 Assertion `src' fails in my_strnxfrm_unicode on GROUP BY MID(..) WITH ROLLUP
+#
+SELECT @@collation_connection;
+@@collation_connection
+utf32_bin
+CREATE TABLE t1 (i INT) ENGINE=MyISAM;
+INSERT INTO t1 VALUES (1),(2);
+SELECT * FROM t1 GROUP BY MID(CURRENT_USER,0) WITH ROLLUP;
+i
+1
+1
+SELECT * FROM t1 GROUP BY MID('test',0) WITH ROLLUP;
+i
+1
+1
+DROP TABLE t1;
+#
 # Bug#55980 Character sets: supplementary character _bin ordering is wrong
 #
 CREATE TABLE t1 AS SELECT REPEAT('a',1) AS a LIMIT 0;
diff --git a/mysql-test/r/ctype_utf32_uca.result b/mysql-test/r/ctype_utf32_uca.result
index 56015076a63..7ea23bb0a08 100644
--- a/mysql-test/r/ctype_utf32_uca.result
+++ b/mysql-test/r/ctype_utf32_uca.result
@@ -2857,6 +2857,23 @@ utf32_unicode_ci	0000006100000009
 utf32_unicode_ci	00000061
 utf32_unicode_ci	0000006100000020
 drop table t1;
+#
+# MDEV-5453 Assertion `src' fails in my_strnxfrm_unicode on GROUP BY MID(..) WITH ROLLUP
+#
+SELECT @@collation_connection;
+@@collation_connection
+utf32_unicode_ci
+CREATE TABLE t1 (i INT) ENGINE=MyISAM;
+INSERT INTO t1 VALUES (1),(2);
+SELECT * FROM t1 GROUP BY MID(CURRENT_USER,0) WITH ROLLUP;
+i
+1
+1
+SELECT * FROM t1 GROUP BY MID('test',0) WITH ROLLUP;
+i
+1
+1
+DROP TABLE t1;
 select @@collation_connection;
 @@collation_connection
 utf32_unicode_ci
diff --git a/mysql-test/r/ctype_utf8.result b/mysql-test/r/ctype_utf8.result
index f98fe649f80..4d558b2902c 100644
--- a/mysql-test/r/ctype_utf8.result
+++ b/mysql-test/r/ctype_utf8.result
@@ -946,6 +946,23 @@ utf8_general_ci	6109
 utf8_general_ci	61
 utf8_general_ci	6120
 drop table t1;
+#
+# MDEV-5453 Assertion `src' fails in my_strnxfrm_unicode on GROUP BY MID(..) WITH ROLLUP
+#
+SELECT @@collation_connection;
+@@collation_connection
+utf8_general_ci
+CREATE TABLE t1 (i INT) ENGINE=MyISAM;
+INSERT INTO t1 VALUES (1),(2);
+SELECT * FROM t1 GROUP BY MID(CURRENT_USER,0) WITH ROLLUP;
+i
+1
+1
+SELECT * FROM t1 GROUP BY MID('test',0) WITH ROLLUP;
+i
+1
+1
+DROP TABLE t1;
 select @@collation_connection;
 @@collation_connection
 utf8_general_ci
@@ -1109,6 +1126,23 @@ utf8_bin	6109
 utf8_bin	61
 utf8_bin	6120
 drop table t1;
+#
+# MDEV-5453 Assertion `src' fails in my_strnxfrm_unicode on GROUP BY MID(..) WITH ROLLUP
+#
+SELECT @@collation_connection;
+@@collation_connection
+utf8_bin
+CREATE TABLE t1 (i INT) ENGINE=MyISAM;
+INSERT INTO t1 VALUES (1),(2);
+SELECT * FROM t1 GROUP BY MID(CURRENT_USER,0) WITH ROLLUP;
+i
+1
+1
+SELECT * FROM t1 GROUP BY MID('test',0) WITH ROLLUP;
+i
+1
+1
+DROP TABLE t1;
 select @@collation_connection;
 @@collation_connection
 utf8_bin
diff --git a/mysql-test/r/ctype_utf8mb4.result b/mysql-test/r/ctype_utf8mb4.result
index 4580d90c5bc..73ceae39295 100644
--- a/mysql-test/r/ctype_utf8mb4.result
+++ b/mysql-test/r/ctype_utf8mb4.result
@@ -946,6 +946,23 @@ utf8mb4_general_ci	6109
 utf8mb4_general_ci	61
 utf8mb4_general_ci	6120
 drop table t1;
+#
+# MDEV-5453 Assertion `src' fails in my_strnxfrm_unicode on GROUP BY MID(..) WITH ROLLUP
+#
+SELECT @@collation_connection;
+@@collation_connection
+utf8mb4_general_ci
+CREATE TABLE t1 (i INT) ENGINE=MyISAM;
+INSERT INTO t1 VALUES (1),(2);
+SELECT * FROM t1 GROUP BY MID(CURRENT_USER,0) WITH ROLLUP;
+i
+1
+1
+SELECT * FROM t1 GROUP BY MID('test',0) WITH ROLLUP;
+i
+1
+1
+DROP TABLE t1;
 select @@collation_connection;
 @@collation_connection
 utf8mb4_general_ci
@@ -1091,6 +1108,23 @@ utf8mb4_bin	61
 utf8mb4_bin	6120
 drop table t1;
 #
+# MDEV-5453 Assertion `src' fails in my_strnxfrm_unicode on GROUP BY MID(..) WITH ROLLUP
+#
+SELECT @@collation_connection;
+@@collation_connection
+utf8mb4_bin
+CREATE TABLE t1 (i INT) ENGINE=MyISAM;
+INSERT INTO t1 VALUES (1),(2);
+SELECT * FROM t1 GROUP BY MID(CURRENT_USER,0) WITH ROLLUP;
+i
+1
+1
+SELECT * FROM t1 GROUP BY MID('test',0) WITH ROLLUP;
+i
+1
+1
+DROP TABLE t1;
+#
 # Bug#55980 Character sets: supplementary character _bin ordering is wrong
 #
 CREATE TABLE t1 AS SELECT REPEAT('a',1) AS a LIMIT 0;
diff --git a/mysql-test/r/ctype_utf8mb4_heap.result b/mysql-test/r/ctype_utf8mb4_heap.result
index bcacdd4e16e..18c8ec69f83 100644
--- a/mysql-test/r/ctype_utf8mb4_heap.result
+++ b/mysql-test/r/ctype_utf8mb4_heap.result
@@ -885,6 +885,23 @@ utf8mb4_general_ci	6109
 utf8mb4_general_ci	61
 utf8mb4_general_ci	6120
 drop table t1;
+#
+# MDEV-5453 Assertion `src' fails in my_strnxfrm_unicode on GROUP BY MID(..) WITH ROLLUP
+#
+SELECT @@collation_connection;
+@@collation_connection
+utf8mb4_general_ci
+CREATE TABLE t1 (i INT) ENGINE=MyISAM;
+INSERT INTO t1 VALUES (1),(2);
+SELECT * FROM t1 GROUP BY MID(CURRENT_USER,0) WITH ROLLUP;
+i
+1
+1
+SELECT * FROM t1 GROUP BY MID('test',0) WITH ROLLUP;
+i
+1
+1
+DROP TABLE t1;
 select @@collation_connection;
 @@collation_connection
 utf8mb4_general_ci
@@ -1029,6 +1046,23 @@ utf8mb4_bin	6109
 utf8mb4_bin	61
 utf8mb4_bin	6120
 drop table t1;
+#
+# MDEV-5453 Assertion `src' fails in my_strnxfrm_unicode on GROUP BY MID(..) WITH ROLLUP
+#
+SELECT @@collation_connection;
+@@collation_connection
+utf8mb4_bin
+CREATE TABLE t1 (i INT) ENGINE=MyISAM;
+INSERT INTO t1 VALUES (1),(2);
+SELECT * FROM t1 GROUP BY MID(CURRENT_USER,0) WITH ROLLUP;
+i
+1
+1
+SELECT * FROM t1 GROUP BY MID('test',0) WITH ROLLUP;
+i
+1
+1
+DROP TABLE t1;
 select @@collation_connection;
 @@collation_connection
 utf8mb4_bin
diff --git a/mysql-test/r/ctype_utf8mb4_innodb.result b/mysql-test/r/ctype_utf8mb4_innodb.result
index 2375ca3bb92..68986e28dea 100644
--- a/mysql-test/r/ctype_utf8mb4_innodb.result
+++ b/mysql-test/r/ctype_utf8mb4_innodb.result
@@ -946,6 +946,23 @@ utf8mb4_general_ci	6109
 utf8mb4_general_ci	61
 utf8mb4_general_ci	6120
 drop table t1;
+#
+# MDEV-5453 Assertion `src' fails in my_strnxfrm_unicode on GROUP BY MID(..) WITH ROLLUP
+#
+SELECT @@collation_connection;
+@@collation_connection
+utf8mb4_general_ci
+CREATE TABLE t1 (i INT) ENGINE=MyISAM;
+INSERT INTO t1 VALUES (1),(2);
+SELECT * FROM t1 GROUP BY MID(CURRENT_USER,0) WITH ROLLUP;
+i
+1
+1
+SELECT * FROM t1 GROUP BY MID('test',0) WITH ROLLUP;
+i
+1
+1
+DROP TABLE t1;
 select @@collation_connection;
 @@collation_connection
 utf8mb4_general_ci
@@ -1090,6 +1107,23 @@ utf8mb4_bin	6109
 utf8mb4_bin	61
 utf8mb4_bin	6120
 drop table t1;
+#
+# MDEV-5453 Assertion `src' fails in my_strnxfrm_unicode on GROUP BY MID(..) WITH ROLLUP
+#
+SELECT @@collation_connection;
+@@collation_connection
+utf8mb4_bin
+CREATE TABLE t1 (i INT) ENGINE=MyISAM;
+INSERT INTO t1 VALUES (1),(2);
+SELECT * FROM t1 GROUP BY MID(CURRENT_USER,0) WITH ROLLUP;
+i
+1
+1
+SELECT * FROM t1 GROUP BY MID('test',0) WITH ROLLUP;
+i
+1
+1
+DROP TABLE t1;
 select @@collation_connection;
 @@collation_connection
 utf8mb4_bin
diff --git a/mysql-test/r/ctype_utf8mb4_myisam.result b/mysql-test/r/ctype_utf8mb4_myisam.result
index b467f07ece9..8a2de245093 100644
--- a/mysql-test/r/ctype_utf8mb4_myisam.result
+++ b/mysql-test/r/ctype_utf8mb4_myisam.result
@@ -946,6 +946,23 @@ utf8mb4_general_ci	6109
 utf8mb4_general_ci	61
 utf8mb4_general_ci	6120
 drop table t1;
+#
+# MDEV-5453 Assertion `src' fails in my_strnxfrm_unicode on GROUP BY MID(..) WITH ROLLUP
+#
+SELECT @@collation_connection;
+@@collation_connection
+utf8mb4_general_ci
+CREATE TABLE t1 (i INT) ENGINE=MyISAM;
+INSERT INTO t1 VALUES (1),(2);
+SELECT * FROM t1 GROUP BY MID(CURRENT_USER,0) WITH ROLLUP;
+i
+1
+1
+SELECT * FROM t1 GROUP BY MID('test',0) WITH ROLLUP;
+i
+1
+1
+DROP TABLE t1;
 select @@collation_connection;
 @@collation_connection
 utf8mb4_general_ci
@@ -1090,6 +1107,23 @@ utf8mb4_bin	6109
 utf8mb4_bin	61
 utf8mb4_bin	6120
 drop table t1;
+#
+# MDEV-5453 Assertion `src' fails in my_strnxfrm_unicode on GROUP BY MID(..) WITH ROLLUP
+#
+SELECT @@collation_connection;
+@@collation_connection
+utf8mb4_bin
+CREATE TABLE t1 (i INT) ENGINE=MyISAM;
+INSERT INTO t1 VALUES (1),(2);
+SELECT * FROM t1 GROUP BY MID(CURRENT_USER,0) WITH ROLLUP;
+i
+1
+1
+SELECT * FROM t1 GROUP BY MID('test',0) WITH ROLLUP;
+i
+1
+1
+DROP TABLE t1;
 select @@collation_connection;
 @@collation_connection
 utf8mb4_bin
diff --git a/mysql-test/suite/binlog/r/binlog_row_ctype_cp932.result b/mysql-test/suite/binlog/r/binlog_row_ctype_cp932.result
index 43108222866..8bdad1813ea 100644
--- a/mysql-test/suite/binlog/r/binlog_row_ctype_cp932.result
+++ b/mysql-test/suite/binlog/r/binlog_row_ctype_cp932.result
@@ -11418,6 +11418,23 @@ cp932_japanese_ci	6109
 cp932_japanese_ci	61
 cp932_japanese_ci	6120
 drop table t1;
+#
+# MDEV-5453 Assertion `src' fails in my_strnxfrm_unicode on GROUP BY MID(..) WITH ROLLUP
+#
+SELECT @@collation_connection;
+@@collation_connection
+cp932_japanese_ci
+CREATE TABLE t1 (i INT) ENGINE=MyISAM;
+INSERT INTO t1 VALUES (1),(2);
+SELECT * FROM t1 GROUP BY MID(CURRENT_USER,0) WITH ROLLUP;
+i
+1
+1
+SELECT * FROM t1 GROUP BY MID('test',0) WITH ROLLUP;
+i
+1
+1
+DROP TABLE t1;
 CREATE TABLE t1 AS
 SELECT 10 AS a, REPEAT('a',20) AS b, REPEAT('a',8) AS c, REPEAT('a',8) AS d;
 ALTER TABLE t1 ADD PRIMARY KEY(a), ADD KEY(b);
@@ -11445,6 +11462,23 @@ cp932_bin	6109
 cp932_bin	61
 cp932_bin	6120
 drop table t1;
+#
+# MDEV-5453 Assertion `src' fails in my_strnxfrm_unicode on GROUP BY MID(..) WITH ROLLUP
+#
+SELECT @@collation_connection;
+@@collation_connection
+cp932_bin
+CREATE TABLE t1 (i INT) ENGINE=MyISAM;
+INSERT INTO t1 VALUES (1),(2);
+SELECT * FROM t1 GROUP BY MID(CURRENT_USER,0) WITH ROLLUP;
+i
+1
+1
+SELECT * FROM t1 GROUP BY MID('test',0) WITH ROLLUP;
+i
+1
+1
+DROP TABLE t1;
 CREATE TABLE t1 AS
 SELECT 10 AS a, REPEAT('a',20) AS b, REPEAT('a',8) AS c, REPEAT('a',8) AS d;
 ALTER TABLE t1 ADD PRIMARY KEY(a), ADD KEY(b);
diff --git a/mysql-test/suite/binlog/r/binlog_stm_ctype_cp932.result b/mysql-test/suite/binlog/r/binlog_stm_ctype_cp932.result
index 43108222866..8bdad1813ea 100644
--- a/mysql-test/suite/binlog/r/binlog_stm_ctype_cp932.result
+++ b/mysql-test/suite/binlog/r/binlog_stm_ctype_cp932.result
@@ -11418,6 +11418,23 @@ cp932_japanese_ci	6109
 cp932_japanese_ci	61
 cp932_japanese_ci	6120
 drop table t1;
+#
+# MDEV-5453 Assertion `src' fails in my_strnxfrm_unicode on GROUP BY MID(..) WITH ROLLUP
+#
+SELECT @@collation_connection;
+@@collation_connection
+cp932_japanese_ci
+CREATE TABLE t1 (i INT) ENGINE=MyISAM;
+INSERT INTO t1 VALUES (1),(2);
+SELECT * FROM t1 GROUP BY MID(CURRENT_USER,0) WITH ROLLUP;
+i
+1
+1
+SELECT * FROM t1 GROUP BY MID('test',0) WITH ROLLUP;
+i
+1
+1
+DROP TABLE t1;
 CREATE TABLE t1 AS
 SELECT 10 AS a, REPEAT('a',20) AS b, REPEAT('a',8) AS c, REPEAT('a',8) AS d;
 ALTER TABLE t1 ADD PRIMARY KEY(a), ADD KEY(b);
@@ -11445,6 +11462,23 @@ cp932_bin	6109
 cp932_bin	61
 cp932_bin	6120
 drop table t1;
+#
+# MDEV-5453 Assertion `src' fails in my_strnxfrm_unicode on GROUP BY MID(..) WITH ROLLUP
+#
+SELECT @@collation_connection;
+@@collation_connection
+cp932_bin
+CREATE TABLE t1 (i INT) ENGINE=MyISAM;
+INSERT INTO t1 VALUES (1),(2);
+SELECT * FROM t1 GROUP BY MID(CURRENT_USER,0) WITH ROLLUP;
+i
+1
+1
+SELECT * FROM t1 GROUP BY MID('test',0) WITH ROLLUP;
+i
+1
+1
+DROP TABLE t1;
 CREATE TABLE t1 AS
 SELECT 10 AS a, REPEAT('a',20) AS b, REPEAT('a',8) AS c, REPEAT('a',8) AS d;
 ALTER TABLE t1 ADD PRIMARY KEY(a), ADD KEY(b);
diff --git a/strings/ctype-utf8.c b/strings/ctype-utf8.c
index 159299a9ea0..e564a85c828 100644
--- a/strings/ctype-utf8.c
+++ b/strings/ctype-utf8.c
@@ -4596,7 +4596,7 @@ my_strnxfrm_unicode(CHARSET_INFO *cs,
   MY_UNICASE_INFO *uni_plane= (cs->state & MY_CS_BINSORT) ?
                                NULL : cs->caseinfo;
   LINT_INIT(wc);
-  DBUG_ASSERT(src);
+  DBUG_ASSERT(!srclen || src);
 
   for (; dst < de && nweights; nweights--)
   {
@@ -4648,7 +4648,7 @@ my_strnxfrm_unicode_full_bin(CHARSET_INFO *cs,
   const uchar *se = src + srclen;
 
   LINT_INIT(wc);
-  DBUG_ASSERT(src);
+  DBUG_ASSERT(!srclen || src);
   DBUG_ASSERT(cs->state & MY_CS_BINSORT);
 
   for ( ; dst < de && nweights; nweights--)