diff --git a/src/widgets/tree_widget.h b/src/widgets/tree_widget.h
--- a/src/widgets/tree_widget.h
+++ b/src/widgets/tree_widget.h
@@ -12,20 +12,20 @@
 #ifndef WIDGETS_TREE_WIDGET_H
 #define WIDGETS_TREE_WIDGET_H
 
-/** Widgets of the WC_BUILD_TREES. */
+/** Widgets of the #BuildTreesWindow class. */
 enum BuildTreesWidgets {
 	WID_BT_TYPE_11,         ///< Tree 1st column 1st row.
 	WID_BT_TYPE_12,         ///< Tree 1st column 2nd row.
 	WID_BT_TYPE_13,         ///< Tree 1st column 3rd row.
 	WID_BT_TYPE_14,         ///< Tree 1st column 4th row.
-	WID_BT_TYPE_21,         ///< Tree 1st column 1st row.
-	WID_BT_TYPE_22,         ///< Tree 1st column 2nd row.
-	WID_BT_TYPE_23,         ///< Tree 1st column 3rd row.
-	WID_BT_TYPE_24,         ///< Tree 1st column 4th row.
-	WID_BT_TYPE_31,         ///< Tree 1st column 1st row.
-	WID_BT_TYPE_32,         ///< Tree 1st column 2nd row.
-	WID_BT_TYPE_33,         ///< Tree 1st column 3rd row.
-	WID_BT_TYPE_34,         ///< Tree 1st column 4th row.
+	WID_BT_TYPE_21,         ///< Tree 2st column 1st row.
+	WID_BT_TYPE_22,         ///< Tree 2st column 2nd row.
+	WID_BT_TYPE_23,         ///< Tree 2st column 3rd row.
+	WID_BT_TYPE_24,         ///< Tree 2st column 4th row.
+	WID_BT_TYPE_31,         ///< Tree 3st column 1st row.
+	WID_BT_TYPE_32,         ///< Tree 3st column 2nd row.
+	WID_BT_TYPE_33,         ///< Tree 3st column 3rd row.
+	WID_BT_TYPE_34,         ///< Tree 3st column 4th row.
 	WID_BT_TYPE_RANDOM,     ///< Button to build random type of tree.
 	WID_BT_MANY_RANDOM,     ///< Button to build many random trees.
 };