diff --git a/vcg/complex/trimesh/create/mc_trivial_walker.h b/vcg/complex/trimesh/create/mc_trivial_walker.h
index 230419e4..5f9f646e 100644
--- a/vcg/complex/trimesh/create/mc_trivial_walker.h
+++ b/vcg/complex/trimesh/create/mc_trivial_walker.h
@@ -22,6 +22,7 @@
 ****************************************************************************/
 #ifndef __VCG_TRIVIAL_WALKER
 #define __VCG_TRIVIAL_WALKER
+#include <vcg/callback.h>
 
 namespace vcg {