diff --git a/core/filter_api.php b/core/filter_api.php
index 7ec05f9..55eda21 100644
--- a/core/filter_api.php
+++ b/core/filter_api.php
@@ -919,7 +919,7 @@ function filter_get_query_sort_data( &$p_filter, $p_show_sticky, $p_query_clause
 
 				$c_cf_alias = str_replace( ' ', '_', $t_custom_field );
 				$t_cf_table_alias = $t_custom_field_string_table . '_' . $t_custom_field_id;
-				$t_cf_select = "$t_cf_table_alias.value $c_cf_alias";
+				$t_cf_select = "$t_cf_table_alias.value `$c_cf_alias`";
 
 				# check to be sure this field wasn't already added to the query.
 				if( !in_array( $t_cf_select, $p_query_clauses['select'] ) ) {
@@ -927,7 +927,7 @@ function filter_get_query_sort_data( &$p_filter, $p_show_sticky, $p_query_clause
 					$p_query_clauses['join'][] = "LEFT JOIN $t_custom_field_string_table $t_cf_table_alias ON $t_bug_table.id = $t_cf_table_alias.bug_id AND $t_cf_table_alias.field_id = $t_custom_field_id";
 				}
 
-				$p_query_clauses['order'][] = "$c_cf_alias $c_dir";
+				$p_query_clauses['order'][] = "`$c_cf_alias` $c_dir";
 
 			# if sorting by plugin columns
 			} else if ( isset( $t_plugin_columns[ $t_sort_fields[$i] ] ) ) {