--- src/vsp/CMakeLists.txt.orig	2014-08-08 15:23:12.000000000 +0200
+++ src/vsp/CMakeLists.txt	2014-08-08 15:23:59.000000000 +0200
@@ -216,6 +216,7 @@
     ${FLTK_LIBRARIES}
     ${OPENGL_LIBRARIES}
     ${OPENNURBS_LIBRARIES}
+    -pthread
 )
 
 INSTALL( TARGETS vsp RUNTIME DESTINATION . )
