diff --git a/mysql-test/r/func_str.result b/mysql-test/r/func_str.result
index 1485809ba70..1042840fe04 100644
--- a/mysql-test/r/func_str.result
+++ b/mysql-test/r/func_str.result
@@ -33,6 +33,9 @@ instr('hello','HE')	instr('hello',binary 'HE')	instr(binary 'hello','HE')
 select position(binary 'll' in 'hello'),position('a' in binary 'hello');
 position(binary 'll' in 'hello')	position('a' in binary 'hello')
 3	0
+select left('hello',null), right('hello',null);
+left('hello',null)	right('hello',null)
+NULL	NULL
 select left('hello',2),right('hello',2),substring('hello',2,2),mid('hello',1,5) ;
 left('hello',2)	right('hello',2)	substring('hello',2,2)	mid('hello',1,5)
 he	lo	el	hello
diff --git a/mysql-test/t/func_str.test b/mysql-test/t/func_str.test
index b13fe039261..56a03283d3a 100644
--- a/mysql-test/t/func_str.test
+++ b/mysql-test/t/func_str.test
@@ -19,6 +19,11 @@ select hex(char(256));
 select locate('he','hello'),locate('he','hello',2),locate('lo','hello',2) ;
 select instr('hello','HE'), instr('hello',binary 'HE'), instr(binary 'hello','HE'); 
 select position(binary 'll' in 'hello'),position('a' in binary 'hello');
+#
+# Bug#11728 string function LEFT,
+# strange undocumented behaviour, strict mode
+#
+select left('hello',null), right('hello',null);
 select left('hello',2),right('hello',2),substring('hello',2,2),mid('hello',1,5) ;
 select concat('',left(right(concat('what ',concat('is ','happening')),9),4),'',substring('monty',5,1)) ;
 select substring_index('www.tcx.se','.',-2),substring_index('www.tcx.se','.',1);
diff --git a/sql-common/client.c b/sql-common/client.c
index 31e85475f08..66d409cf1eb 100644
--- a/sql-common/client.c
+++ b/sql-common/client.c
@@ -1673,11 +1673,18 @@ C_MODE_START
 int mysql_init_character_set(MYSQL *mysql)
 {
   NET		*net= &mysql->net;
+  const char *default_collation_name;
+  
   /* Set character set */
-  if (!mysql->options.charset_name &&
-      !(mysql->options.charset_name= 
+  if (!mysql->options.charset_name)
+  {
+    default_collation_name= MYSQL_DEFAULT_COLLATION_NAME;
+    if (!(mysql->options.charset_name= 
        my_strdup(MYSQL_DEFAULT_CHARSET_NAME,MYF(MY_WME))))
     return 1;
+  }
+  else
+    default_collation_name= NULL;
   
   {
     const char *save= charsets_dir;
@@ -1685,6 +1692,28 @@ int mysql_init_character_set(MYSQL *mysql)
       charsets_dir=mysql->options.charset_dir;
     mysql->charset=get_charset_by_csname(mysql->options.charset_name,
                                          MY_CS_PRIMARY, MYF(MY_WME));
+    if (mysql->charset && default_collation_name)
+    {
+      CHARSET_INFO *collation;
+      if ((collation= 
+           get_charset_by_name(default_collation_name, MYF(MY_WME))))
+      {
+        if (!my_charset_same(mysql->charset, collation))
+        {
+          my_printf_error(ER_UNKNOWN_ERROR, 
+                         "COLLATION %s is not valid for CHARACTER SET %s",
+                         MYF(0),
+                         default_collation_name, mysql->options.charset_name);
+          mysql->charset= NULL;
+        }
+        else
+        {
+          mysql->charset= collation;
+        }
+      }
+      else
+        mysql->charset= NULL;
+    }
     charsets_dir= save;
   }
   
diff --git a/sql/item_strfunc.cc b/sql/item_strfunc.cc
index 9e3a9b64288..5aef789074f 100644
--- a/sql/item_strfunc.cc
+++ b/sql/item_strfunc.cc
@@ -1038,7 +1038,7 @@ String *Item_func_left::val_str(String *str)
   long length  =(long) args[1]->val_int();
   uint char_pos;
 
-  if ((null_value=args[0]->null_value))
+  if ((null_value=(args[0]->null_value || args[1]->null_value)))
     return 0;
   if (length <= 0)
     return &my_empty_string;
@@ -1078,7 +1078,7 @@ String *Item_func_right::val_str(String *str)
   String *res  =args[0]->val_str(str);
   long length  =(long) args[1]->val_int();
 
-  if ((null_value=args[0]->null_value))
+  if ((null_value=(args[0]->null_value || args[1]->null_value)))
     return 0; /* purecov: inspected */
   if (length <= 0)
     return &my_empty_string; /* purecov: inspected */