--- make/build.xml	2022-04-04 16:31:19.979033720 +0000
+++ make/build.xml	2022-04-04 16:48:11.871782712 +0000
@@ -733,13 +733,13 @@
       <!-- linker configuration -->
  
       <linker id="linker.cfg.linux.jogl" extends="linker.cfg.linux">
-        <syslibset dir="/usr/X11R6/lib" libs="GL, X11"/>
+        <syslibset dir="/usr/X11R6/lib" libs="GL, X11, Xext"/>
         <syslibset dir="/usr/X11R6/lib" libs="Xxf86vm" />
         <syslibset dir="${x11.cg.lib}" libs="Cg, CgGL" if="c.compiler.use-cglib"/>
       </linker>
 
       <linker id="linker.cfg.linux.amd64.jogl" name="gcc">
-        <syslibset dir="/usr/X11R6/lib64" libs="GL, X11"/>
+        <syslibset dir="/usr/X11R6/lib64" libs="GL, X11, Xext"/>
         <syslibset dir="/usr/X11R6/lib64" libs="Xxf86vm" />
         <syslibset dir="${x11.cg.lib}" libs="Cg, CgGL" if="c.compiler.use-cglib"/>
       </linker>