diff --git a/include/my_base.h b/include/my_base.h
index 22587ec8be1..fadeffd3fde 100644
--- a/include/my_base.h
+++ b/include/my_base.h
@@ -334,6 +334,7 @@ is the global server default. */
 #define HA_OPTION_NO_STATS_PERSISTENT	8192
 #define HA_OPTION_TEMP_COMPRESS_RECORD	((uint) 16384)	/* set by isamchk */
 #define HA_OPTION_READ_ONLY_DATA	((uint) 32768)	/* Set by isamchk */
+#define HA_OPTION_PACK_KEYS_NOT_SUPPORTED		((uint) 65536)
 
 	/* Bits in flag to create() */
 
diff --git a/sql/sql_table.cc b/sql/sql_table.cc
index b1bf21a76a7..4ab2b1846b8 100644
--- a/sql/sql_table.cc
+++ b/sql/sql_table.cc
@@ -3493,6 +3493,9 @@ mysql_prepare_create_table(THD *thd, const char *error_schema_name,
   uint total_uneven_bit_length= 0;
   DBUG_ENTER("mysql_prepare_create_table");
 
+  if (create_info->db_type->db_type == DB_TYPE_INNODB)
+      *db_options |= HA_OPTION_PACK_KEYS_NOT_SUPPORTED;
+
   LEX_STRING* connect_string = &create_info->connect_string;
   if (connect_string->length != 0 &&
       connect_string->length > CONNECT_STRING_MAXLEN &&
@@ -4412,6 +4415,7 @@ mysql_prepare_create_table(THD *thd, const char *error_schema_name,
       key_part_info->length= (uint16) key_part_length;
       /* Use packed keys for long strings on the first column */
       if (!((*db_options) & HA_OPTION_NO_PACK_KEYS) &&
+          !((*db_options) & HA_OPTION_PACK_KEYS_NOT_SUPPORTED) &&
           !((create_info->table_options & HA_OPTION_NO_PACK_KEYS)) &&
 	  (key_part_length >= KEY_DEFAULT_PACK_LENGTH &&
 	   (sql_field->sql_type == MYSQL_TYPE_STRING ||
@@ -6248,8 +6252,13 @@ static bool has_index_def_changed(Alter_inplace_info *ha_alter_info,
       check lengths first as in case when fields differ it is likely
       that lengths differ too and checking fields is more expensive
       in general case.
+      We allow InnoDB VARCHAR extension as long as the number of length
+      indicator bytes does not change.
     */
-    if (key_part->length != new_part->length)
+    if (key_part->length != new_part->length
+        && ! (ha_alter_info->handler_flags &
+              Alter_inplace_info::ALTER_COLUMN_EQUAL_PACK_LENGTH)
+       )
       return true;
 
     new_field= get_field_by_index(alter_info, new_part->fieldnr);