diff --git a/vcg/complex/algorithms/smooth.h b/vcg/complex/algorithms/smooth.h
index b3515c7d..f98e89ea 100644
--- a/vcg/complex/algorithms/smooth.h
+++ b/vcg/complex/algorithms/smooth.h
@@ -25,6 +25,7 @@
 #ifndef __VCGLIB__SMOOTH
 #define __VCGLIB__SMOOTH
 
+#include <cmath>
 #include <wrap/callback.h>
 #include <vcg/space/point3.h>
 #include <vcg/space/ray3.h>