diff -up ./libstage/stage.hh.gcc6 ./libstage/stage.hh
--- ./libstage/stage.hh.gcc6	2012-01-11 21:06:07.000000000 -0500
+++ ./libstage/stage.hh	2016-04-03 14:26:45.983820363 -0400
@@ -622,46 +622,46 @@ namespace Stg
   { cont.erase( std::remove( cont.begin(), cont.end(), thing ), cont.end() ); }
   
   // Error macros - output goes to stderr
-#define PRINT_ERR(m) fprintf( stderr, "\033[41merr\033[0m: "m" (%s %s)\n", __FILE__, __FUNCTION__)
-#define PRINT_ERR1(m,a) fprintf( stderr, "\033[41merr\033[0m: "m" (%s %s)\n", a, __FILE__, __FUNCTION__)    
-#define PRINT_ERR2(m,a,b) fprintf( stderr, "\033[41merr\033[0m: "m" (%s %s)\n", a, b, __FILE__, __FUNCTION__) 
-#define PRINT_ERR3(m,a,b,c) fprintf( stderr, "\033[41merr\033[0m: "m" (%s %s)\n", a, b, c, __FILE__, __FUNCTION__)
-#define PRINT_ERR4(m,a,b,c,d) fprintf( stderr, "\033[41merr\033[0m: "m" (%s %s)\n", a, b, c, d, __FILE__, __FUNCTION__)
-#define PRINT_ERR5(m,a,b,c,d,e) fprintf( stderr, "\033[41merr\033[0m: "m" (%s %s)\n", a, b, c, d, e, __FILE__, __FUNCTION__)
+#define PRINT_ERR(m) fprintf( stderr, "\033[41merr\033[0m: " m " (%s %s)\n", __FILE__, __FUNCTION__)
+#define PRINT_ERR1(m,a) fprintf( stderr, "\033[41merr\033[0m: " m " (%s %s)\n", a, __FILE__, __FUNCTION__)    
+#define PRINT_ERR2(m,a,b) fprintf( stderr, "\033[41merr\033[0m: " m " (%s %s)\n", a, b, __FILE__, __FUNCTION__) 
+#define PRINT_ERR3(m,a,b,c) fprintf( stderr, "\033[41merr\033[0m: " m " (%s %s)\n", a, b, c, __FILE__, __FUNCTION__)
+#define PRINT_ERR4(m,a,b,c,d) fprintf( stderr, "\033[41merr\033[0m: " m " (%s %s)\n", a, b, c, d, __FILE__, __FUNCTION__)
+#define PRINT_ERR5(m,a,b,c,d,e) fprintf( stderr, "\033[41merr\033[0m: " m " (%s %s)\n", a, b, c, d, e, __FILE__, __FUNCTION__)
 
   // Warning macros
-#define PRINT_WARN(m) printf( "\033[44mwarn\033[0m: "m" (%s %s)\n", __FILE__, __FUNCTION__)
-#define PRINT_WARN1(m,a) printf( "\033[44mwarn\033[0m: "m" (%s %s)\n", a, __FILE__, __FUNCTION__)    
-#define PRINT_WARN2(m,a,b) printf( "\033[44mwarn\033[0m: "m" (%s %s)\n", a, b, __FILE__, __FUNCTION__) 
-#define PRINT_WARN3(m,a,b,c) printf( "\033[44mwarn\033[0m: "m" (%s %s)\n", a, b, c, __FILE__, __FUNCTION__)
-#define PRINT_WARN4(m,a,b,c,d) printf( "\033[44mwarn\033[0m: "m" (%s %s)\n", a, b, c, d, __FILE__, __FUNCTION__)
-#define PRINT_WARN5(m,a,b,c,d,e) printf( "\033[44mwarn\033[0m: "m" (%s %s)\n", a, b, c, d, e, __FILE__, __FUNCTION__)
+#define PRINT_WARN(m) printf( "\033[44mwarn\033[0m: " m " (%s %s)\n", __FILE__, __FUNCTION__)
+#define PRINT_WARN1(m,a) printf( "\033[44mwarn\033[0m: " m " (%s %s)\n", a, __FILE__, __FUNCTION__)    
+#define PRINT_WARN2(m,a,b) printf( "\033[44mwarn\033[0m: " m " (%s %s)\n", a, b, __FILE__, __FUNCTION__) 
+#define PRINT_WARN3(m,a,b,c) printf( "\033[44mwarn\033[0m: " m " (%s %s)\n", a, b, c, __FILE__, __FUNCTION__)
+#define PRINT_WARN4(m,a,b,c,d) printf( "\033[44mwarn\033[0m: " m " (%s %s)\n", a, b, c, d, __FILE__, __FUNCTION__)
+#define PRINT_WARN5(m,a,b,c,d,e) printf( "\033[44mwarn\033[0m: " m " (%s %s)\n", a, b, c, d, e, __FILE__, __FUNCTION__)
 
   // Message macros
 #ifdef DEBUG
-#define PRINT_MSG(m) printf( "Stage: "m" (%s %s)\n", __FILE__, __FUNCTION__)
-#define PRINT_MSG1(m,a) printf( "Stage: "m" (%s %s)\n", a, __FILE__, __FUNCTION__)    
-#define PRINT_MSG2(m,a,b) printf( "Stage: "m" (%s %s)\n", a, b, __FILE__, __FUNCTION__) 
-#define PRINT_MSG3(m,a,b,c) printf( "Stage: "m" (%s %s)\n", a, b, c, __FILE__, __FUNCTION__)
-#define PRINT_MSG4(m,a,b,c,d) printf( "Stage: "m" (%s %s)\n", a, b, c, d, __FILE__, __FUNCTION__)
-#define PRINT_MSG5(m,a,b,c,d,e) printf( "Stage: "m" (%s %s)\n", a, b, c, d, e,__FILE__, __FUNCTION__)
+#define PRINT_MSG(m) printf( "Stage: " m " (%s %s)\n", __FILE__, __FUNCTION__)
+#define PRINT_MSG1(m,a) printf( "Stage: " m " (%s %s)\n", a, __FILE__, __FUNCTION__)    
+#define PRINT_MSG2(m,a,b) printf( "Stage: " m " (%s %s)\n", a, b, __FILE__, __FUNCTION__) 
+#define PRINT_MSG3(m,a,b,c) printf( "Stage: " m " (%s %s)\n", a, b, c, __FILE__, __FUNCTION__)
+#define PRINT_MSG4(m,a,b,c,d) printf( "Stage: " m " (%s %s)\n", a, b, c, d, __FILE__, __FUNCTION__)
+#define PRINT_MSG5(m,a,b,c,d,e) printf( "Stage: " m " (%s %s)\n", a, b, c, d, e,__FILE__, __FUNCTION__)
 #else
-#define PRINT_MSG(m) printf( "Stage: "m"\n" )
-#define PRINT_MSG1(m,a) printf( "Stage: "m"\n", a)
-#define PRINT_MSG2(m,a,b) printf( "Stage: "m"\n,", a, b )
-#define PRINT_MSG3(m,a,b,c) printf( "Stage: "m"\n", a, b, c )
-#define PRINT_MSG4(m,a,b,c,d) printf( "Stage: "m"\n", a, b, c, d )
-#define PRINT_MSG5(m,a,b,c,d,e) printf( "Stage: "m"\n", a, b, c, d, e )
+#define PRINT_MSG(m) printf( "Stage: " m "\n" )
+#define PRINT_MSG1(m,a) printf( "Stage: " m "\n", a)
+#define PRINT_MSG2(m,a,b) printf( "Stage: " m "\n,", a, b )
+#define PRINT_MSG3(m,a,b,c) printf( "Stage: " m "\n", a, b, c )
+#define PRINT_MSG4(m,a,b,c,d) printf( "Stage: " m "\n", a, b, c, d )
+#define PRINT_MSG5(m,a,b,c,d,e) printf( "Stage: " m "\n", a, b, c, d, e )
 #endif
 
   // DEBUG macros
 #ifdef DEBUG
-#define PRINT_DEBUG(m) printf( "debug: "m" (%s %s)\n", __FILE__, __FUNCTION__)
-#define PRINT_DEBUG1(m,a) printf( "debug: "m" (%s %s)\n", a, __FILE__, __FUNCTION__)    
-#define PRINT_DEBUG2(m,a,b) printf( "debug: "m" (%s %s)\n", a, b, __FILE__, __FUNCTION__) 
-#define PRINT_DEBUG3(m,a,b,c) printf( "debug: "m" (%s %s)\n", a, b, c, __FILE__, __FUNCTION__)
-#define PRINT_DEBUG4(m,a,b,c,d) printf( "debug: "m" (%s %s)\n", a, b, c ,d, __FILE__, __FUNCTION__)
-#define PRINT_DEBUG5(m,a,b,c,d,e) printf( "debug: "m" (%s %s)\n", a, b, c ,d, e, __FILE__, __FUNCTION__)
+#define PRINT_DEBUG(m) printf( "debug: " m " (%s %s)\n", __FILE__, __FUNCTION__)
+#define PRINT_DEBUG1(m,a) printf( "debug: " m " (%s %s)\n", a, __FILE__, __FUNCTION__)    
+#define PRINT_DEBUG2(m,a,b) printf( "debug: " m " (%s %s)\n", a, b, __FILE__, __FUNCTION__) 
+#define PRINT_DEBUG3(m,a,b,c) printf( "debug: " m " (%s %s)\n", a, b, c, __FILE__, __FUNCTION__)
+#define PRINT_DEBUG4(m,a,b,c,d) printf( "debug: " m " (%s %s)\n", a, b, c ,d, __FILE__, __FUNCTION__)
+#define PRINT_DEBUG5(m,a,b,c,d,e) printf( "debug: " m " (%s %s)\n", a, b, c ,d, e, __FILE__, __FUNCTION__)
 #else
 #define PRINT_DEBUG(m)
 #define PRINT_DEBUG1(m,a)
diff -up ./libstage/world.cc.gcc6 ./libstage/world.cc
--- ./libstage/world.cc.gcc6	2016-04-03 14:33:10.954024890 -0400
+++ ./libstage/world.cc	2016-04-03 14:38:31.788683065 -0400
@@ -803,8 +803,8 @@ RaytraceResult World::Raytrace( const Ra
   // Graphics Gems IV  
   const int32_t sx(sgn(dx));  
   const int32_t sy(sgn(dy));  
-  const int32_t ax(abs(dx)); 
-  const int32_t ay(abs(dy));  
+  const int32_t ax(fabs(dx)); 
+  const int32_t ay(fabs(dy));  
   const int32_t bx(2*ax);	
   const int32_t by(2*ay);	
   int32_t exy(ay-ax); // difference between x and y distances