diff --git a/FL/Fl_Tree.H b/FL/Fl_Tree.H
index 5e6865124..c42718587 100644
--- a/FL/Fl_Tree.H
+++ b/FL/Fl_Tree.H
@@ -130,7 +130,7 @@ enum Fl_Tree_Reason {
 };
 
 
-class Fl_Tree : public Fl_Group {
+class FL_EXPORT Fl_Tree : public Fl_Group {
   Fl_Tree_Item  *_root;				// can be null!
   Fl_Tree_Item  *_item_focus;			// item that has focus box
   Fl_Tree_Item  *_callback_item;		// item invoked during callback (can be NULL)
diff --git a/FL/Fl_Tree_Item.H b/FL/Fl_Tree_Item.H
index 983c8c0ab..434ae303c 100644
--- a/FL/Fl_Tree_Item.H
+++ b/FL/Fl_Tree_Item.H
@@ -56,7 +56,7 @@
 /// When you make changes to items, you'll need to tell the tree to redraw()
 /// for the changes to show up.
 ///
-class Fl_Tree_Item {
+class FL_EXPORT Fl_Tree_Item {
   const char             *_label;		// label (memory managed)
   int                     _labelfont;		// label's font face
   int                     _labelsize;		// label's font size
diff --git a/FL/Fl_Tree_Item_Array.H b/FL/Fl_Tree_Item_Array.H
index 19a28b4dc..efa60acf9 100644
--- a/FL/Fl_Tree_Item_Array.H
+++ b/FL/Fl_Tree_Item_Array.H
@@ -5,7 +5,9 @@
 #ifndef _FL_TREE_ITEM_ARRAY_H
 #define _FL_TREE_ITEM_ARRAY_H
 
-class Fl_Tree_Item;		// forward decl must *precede* first doxygen comment block
+#include "Fl_Export.H"
+
+class FL_EXPORT Fl_Tree_Item;	// forward decl must *precede* first doxygen comment block
 				// or doxygen will not document our class..
 
 //////////////////////////
@@ -46,7 +48,7 @@ class Fl_Tree_Item;		// forward decl must *precede* first doxygen comment block
 /// (unless otherwise noted).
 ///
 
-class Fl_Tree_Item_Array {
+class FL_EXPORT Fl_Tree_Item_Array {
   Fl_Tree_Item **_items;	// items array
   int _total;			// #items in array
   int _size;			// #items *allocated* for array
diff --git a/FL/Fl_Tree_Prefs.H b/FL/Fl_Tree_Prefs.H
index 26b5ef39e..c875e0cc4 100644
--- a/FL/Fl_Tree_Prefs.H
+++ b/FL/Fl_Tree_Prefs.H
@@ -82,7 +82,7 @@ enum Fl_Tree_Select {
 /// You should probably be using the methods in Fl_Tree
 /// instead of trying to accessing tree's preferences settings directly.
 ///
-class Fl_Tree_Prefs {
+class FL_EXPORT Fl_Tree_Prefs {
   int _labelfont;			// label's font face
   int _labelsize;			// label's font size
   int _margintop;			// --