diff --git a/BUILDING.txt b/BUILDING.txt
index e24d604..de0cae2 100644
--- a/BUILDING.txt
+++ b/BUILDING.txt
@@ -112,7 +112,7 @@
 # Notify applications of changes to the clipboard
 # http://www.fltk.org/str.php?L2636
 apply_patch 2636 fltk-1.3.x-clipboard.patch
-apply_patch 2636 fltk-1_v5.3.x-clipboard-x11.patch
+apply_patch 2636 fltk-1_v6.3.x-clipboard-x11.patch
 apply_patch 2636 fltk-1_v3.3.x-clipboard-win32-fix.patch
 apply_patch 2636 fltk-1_v2.3.x-clipboard-win32.patch
 apply_patch 2636 fltk-1_v2.3.x-clipboard-osx.patch