diff --git a/sql/sql_class.cc b/sql/sql_class.cc
index f1c75a3b365..9dcff60dfed 100644
--- a/sql/sql_class.cc
+++ b/sql/sql_class.cc
@@ -222,7 +222,7 @@ THD::THD()
 
   init();
   /* Initialize sub structures */
-  init_alloc_root(&warn_root, WARN_ALLOC_BLOCK_SIZE, WARN_ALLOC_PREALLOC_SIZE);
+  init_sql_alloc(&warn_root, WARN_ALLOC_BLOCK_SIZE, WARN_ALLOC_PREALLOC_SIZE);
   user_connect=(USER_CONN *)0;
   hash_init(&user_vars, &my_charset_bin, USER_VARS_HASH_SIZE, 0, 0,
 	    (hash_get_key) get_var_key,
@@ -258,7 +258,7 @@ THD::THD()
     transaction.trans_log.end_of_file= max_binlog_cache_size;
   }
 #endif
-  init_alloc_root(&transaction.mem_root, ALLOC_ROOT_MIN_BLOCK_SIZE, 0);
+  init_sql_alloc(&transaction.mem_root, ALLOC_ROOT_MIN_BLOCK_SIZE, 0);
   {
     ulong tmp=sql_rnd_with_mutex();
     randominit(&rand, tmp + (ulong) &rand, tmp + (ulong) ::query_id);
@@ -1421,7 +1421,7 @@ Item_arena::Item_arena(bool init_mem_root)
   state(CONVENTIONAL_EXECUTION)
 {
   if (init_mem_root)
-    init_alloc_root(&mem_root, ALLOC_ROOT_MIN_BLOCK_SIZE, 0);
+    init_sql_alloc(&mem_root, ALLOC_ROOT_MIN_BLOCK_SIZE, 0);
 }
 
 
diff --git a/sql/sql_parse.cc b/sql/sql_parse.cc
index a01b8c895c3..e407865f715 100644
--- a/sql/sql_parse.cc
+++ b/sql/sql_parse.cc
@@ -2018,6 +2018,7 @@ mysql_execute_command(THD *thd)
       CHARSET_INFO *to_cs= thd->variables.collation_connection;
       bool need_conversion;
       user_var_entry *entry;
+      String *pstr= &str;
       uint32 unused;
       /*
         Convert @var contents to string in connection character set. Although
@@ -2033,26 +2034,43 @@ mysql_execute_command(THD *thd)
         String *pstr;
         my_bool is_var_null;
         pstr= entry->val_str(&is_var_null, &str, NOT_FIXED_DEC);
+        /*
+          NULL value of variable checked early as entry->value so here
+          we can't get NULL in normal conditions
+        */
         DBUG_ASSERT(!is_var_null);
         if (!pstr)
-          send_error(thd, ER_OUT_OF_RESOURCES);
-        DBUG_ASSERT(pstr == &str);
+        {
+          res= -1;
+          break;      // EOM (error should be reported by allocator)
+        }
       }
       else
+      {
+        /*
+          variable absent or equal to NULL, so we need to set variable to
+          something reasonable to get readable error message during parsing
+        */
         str.set("NULL", 4, &my_charset_latin1);
-      need_conversion=
-        String::needs_conversion(str.length(), str.charset(), to_cs, &unused);
+      }
 
-      query_len= need_conversion? (str.length() * to_cs->mbmaxlen) :
-                                  str.length();
+      need_conversion=
+        String::needs_conversion(pstr->length(), pstr->charset(),
+                                 to_cs, &unused);
+
+      query_len= need_conversion? (pstr->length() * to_cs->mbmaxlen) :
+                                  pstr->length();
       if (!(query_str= alloc_root(&thd->mem_root, query_len+1)))
-        send_error(thd, ER_OUT_OF_RESOURCES);
+      {
+        res= -1;
+        break;        // EOM (error should be reported by allocator)
+      }
 
       if (need_conversion)
-        query_len= copy_and_convert(query_str, query_len, to_cs, str.ptr(),
-                                    str.length(), str.charset());
+        query_len= copy_and_convert(query_str, query_len, to_cs, pstr->ptr(),
+                                    pstr->length(), pstr->charset());
       else
-        memcpy(query_str, str.ptr(), str.length());
+        memcpy(query_str, pstr->ptr(), pstr->length());
       query_str[query_len]= 0;
     }
     else