diff --git a/sql/sql_table.cc b/sql/sql_table.cc
index e86ebba561288..32e371b1ba292 100644
--- a/sql/sql_table.cc
+++ b/sql/sql_table.cc
@@ -3067,11 +3067,10 @@ my_bool init_key_info(THD *thd, Alter_info *alter_info,
 
       if (is_hash_field_needed)
       {
-        if (key_cinfo->algorithm == HA_KEY_ALG_UNDEF)
+        if (key_cinfo->algorithm == HA_KEY_ALG_UNDEF || key_cinfo->algorithm == HA_KEY_ALG_HASH)
           key_cinfo->algorithm= HA_KEY_ALG_LONG_HASH;
 
-        if (key_cinfo->algorithm != HA_KEY_ALG_HASH &&
-            key_cinfo->algorithm != HA_KEY_ALG_LONG_HASH)
+        if (key_cinfo->algorithm != HA_KEY_ALG_LONG_HASH)
         {
           my_error(ER_TOO_LONG_KEY, MYF(0), max_key_length);
           DBUG_RETURN(TRUE);
@@ -9163,7 +9162,7 @@ mysql_prepare_alter_table(THD *thd, TABLE *table,
       LEX_CSTRING tmp_name;
       bzero((char*) &key_create_info, sizeof(key_create_info));
       if (key_info->algorithm == HA_KEY_ALG_LONG_HASH)
-        key_info->algorithm= alter_ctx->fast_alter_partition ?
+        key_info->algorithm= (alter_ctx->fast_alter_partition || !(alter_info->flags & ALTER_CHANGE_COLUMN)) ?
           HA_KEY_ALG_HASH : HA_KEY_ALG_UNDEF;
       /*
         For fast alter partition we set HA_KEY_ALG_HASH above to make sure it