Index: mttroot/mtt/lib/cr/hh/lin.hh
==================================================================
--- mttroot/mtt/lib/cr/hh/lin.hh
+++ mttroot/mtt/lib/cr/hh/lin.hh
@@ -1,10 +1,11 @@
 #ifndef LIN_HH
 #define LIN_HH
 
 #include <iostream>
 
+#include "causality.hh"
 #include "components.hh"
 // translated from lin.cr
 
 // one 2-port, R/C/I; two 2-port, TF/GY
 inline double

Index: mttroot/mtt/lib/cr/hh/pressuredrop.hh
==================================================================
--- mttroot/mtt/lib/cr/hh/pressuredrop.hh
+++ mttroot/mtt/lib/cr/hh/pressuredrop.hh
@@ -2,10 +2,11 @@
 #define PRESSUREDROP_HH
 
 #include <cmath>		// fabs, pow
 #include <string>
 
+#include "causality.hh"
 #include "constants.hh"
 #include "frictionfactor.hh"
 #include "kinematicviscosity.hh"
 #include "sign.hh"
 

Index: mttroot/mtt/lib/cr/hh/squarelaw.hh
==================================================================
--- mttroot/mtt/lib/cr/hh/squarelaw.hh
+++ mttroot/mtt/lib/cr/hh/squarelaw.hh
@@ -1,10 +1,12 @@
 #ifndef SQUARELAW_HH
 #define SQUARELAW_HH
 
 #include <cmath
 #include "sign.hh"
+
+#include "causality.hh"
 
 inline double squarelaw(const double gain,
 			const causality_t causality, const int port,
 			const double input, const causality_t in_causality, const int in_port)
   /*

Index: mttroot/mtt/lib/cr/hh/staticpressure.hh
==================================================================
--- mttroot/mtt/lib/cr/hh/staticpressure.hh
+++ mttroot/mtt/lib/cr/hh/staticpressure.hh
@@ -1,10 +1,11 @@
 #ifndef STATICPRESSURE_HH
 #define STATICPRESSURE_HH
 
 #include <cmath>		// log, pow
 
+#include "causality.hh"
 #include "constants.hh"
 
 inline double
 staticpressure(const double beta,
 	       const double C_d,