diff --git a/MeshLib/Elements/LineRule2.cpp b/MeshLib/Elements/LineRule2.cpp
index fbc833b43d5663e7b905f473b7670c8cab7eaff7..366d43770758d345d588e58387cb39d3425b481c 100644
--- a/MeshLib/Elements/LineRule2.cpp
+++ b/MeshLib/Elements/LineRule2.cpp
@@ -10,6 +10,7 @@
 
 #include "LineRule2.h"
 
+#include "MathLib/MathTools.h"
 #include "MeshLib/Node.h"
 
 namespace MeshLib {