diff -uNr r545.ORIG/Include/Random.hh r545/Include/Random.hh
--- r545.ORIG/Include/Random.hh	2018-04-04 21:00:08.000000000 +0900
+++ r545/Include/Random.hh	2018-04-05 05:43:27.000000000 +0900
@@ -103,7 +103,7 @@
 double RndmHeedWF(const double w, const double f);
 
 /// Draw a random (isotropic) direction vector.
-void RndmDirection(double& dx, double& dy, double& dz,
+inline void RndmDirection(double& dx, double& dy, double& dz,
                    const double length = 1.) {
 
   const double phi = TwoPi * RndmUniform();