diff --git a/vcg/complex/trimesh/update/selection.h b/vcg/complex/trimesh/update/selection.h
index 9888d2d4..c00a5fdc 100644
--- a/vcg/complex/trimesh/update/selection.h
+++ b/vcg/complex/trimesh/update/selection.h
@@ -37,6 +37,8 @@ First Working Version
 #ifndef __VCG_TRI_UPDATE_SELECTION
 #define __VCG_TRI_UPDATE_SELECTION
 
+#include <vcg/complex/trimesh/update/flag.h>
+
 namespace vcg {
 namespace tri {