diff --git a/vcg/complex/base.h b/vcg/complex/base.h
index 827e0597..49f2ff88 100644
--- a/vcg/complex/base.h
+++ b/vcg/complex/base.h
@@ -369,7 +369,7 @@ void Clear()
   C()=Color4b::Gray;
 }
 
-bool IsEmpty()
+bool IsEmpty() const
 {
   return vert.empty() && edge.empty() && face.empty();
 }