diff --git a/sql/rpl_record.cc b/sql/rpl_record.cc
index c2d3ddbc353..7bf7b81aa3a 100644
--- a/sql/rpl_record.cc
+++ b/sql/rpl_record.cc
@@ -150,13 +150,20 @@ pack_row(TABLE *table, MY_BITMAP const* cols,
    the various member functions of Field and subclasses expect to
    write.
 
-   The row is assumed to only consist of the fields for which the corresponding
-   bit in bitset @c cols is set; the other parts of the record are left alone.
+   The row is assumed to only consist of the fields for which the
+   corresponding bit in bitset @c cols is set; the other parts of the
+   record are left alone.
 
    At most @c colcnt columns are read: if the table is larger than
    that, the remaining fields are not filled in.
 
-   @param rli     Relay log info
+   @note The relay log information can be NULL, which means that no
+   checking or comparison with the source table is done, simply
+   because it is not used.  This feature is used by MySQL Backup to
+   unpack a row from from the backup image, but can be used for other
+   purposes as well.
+
+   @param rli     Relay log info, which can be NULL
    @param table   Table to unpack into
    @param colcnt  Number of columns to read from record
    @param row_data
@@ -170,10 +177,8 @@ pack_row(TABLE *table, MY_BITMAP const* cols,
 
    @retval 0 No error
 
-   @retval ER_NO_DEFAULT_FOR_FIELD
-   Returned if one of the fields existing on the slave but not on the
-   master does not have a default value (and isn't nullable)
-
+   @retval HA_ERR_GENERIC
+   A generic, internal, error caused the unpacking to fail.
  */
 #if !defined(MYSQL_CLIENT) && defined(HAVE_REPLICATION)
 int
@@ -185,6 +190,7 @@ unpack_row(Relay_log_info const *rli,
 {
   DBUG_ENTER("unpack_row");
   DBUG_ASSERT(row_data);
+  DBUG_ASSERT(table);
   size_t const master_null_byte_count= (bitmap_bits_set(cols) + 7) / 8;
   int error= 0;
 
@@ -202,14 +208,21 @@ unpack_row(Relay_log_info const *rli,
   // The "current" null bits
   unsigned int null_bits= *null_ptr++;
   uint i= 0;
-  table_def *tabledef;
-  TABLE *conv_table;
-  bool table_found= rli->get_table_data(table, &tabledef, &conv_table);
+  table_def *tabledef= NULL;
+  TABLE *conv_table= NULL;
+  bool table_found= rli && rli->get_table_data(table, &tabledef, &conv_table);
   DBUG_PRINT("debug", ("Table data: table_found: %d, tabldef: %p, conv_table: %p",
                        table_found, tabledef, conv_table));
   DBUG_ASSERT(table_found);
-  if (!table_found)
-    return HA_ERR_GENERIC;
+
+  /*
+    If rli is NULL it means that there is no source table and that the
+    row shall just be unpacked without doing any checks. This feature
+    is used by MySQL Backup, but can be used for other purposes as
+    well.
+   */
+  if (rli && !table_found)
+    DBUG_RETURN(HA_ERR_GENERIC);
 
   for (field_ptr= begin_ptr ; field_ptr < end_ptr && *field_ptr ; ++field_ptr)
   {
diff --git a/sql/rpl_utility.cc b/sql/rpl_utility.cc
index 16eaae9b91d..feb35527b62 100644
--- a/sql/rpl_utility.cc
+++ b/sql/rpl_utility.cc
@@ -592,6 +592,12 @@ can_convert_field_to(Field *field,
   {
     if (metadata == 0) // Metadata can only be zero if no metadata was provided
     {
+      /*
+        If there is no metadata, we either have an old event where no
+        metadata were supplied, or a type that does not require any
+        metadata. In either case, conversion can be done but no
+        conversion table is necessary.
+       */
       DBUG_PRINT("debug", ("Base types are identical, but there is no metadata"));
       *order_var= 0;
       DBUG_RETURN(true);