diff --git a/floorshapes.cpp b/floorshapes.cpp
index f382f5d6..1266b86a 100644
--- a/floorshapes.cpp
+++ b/floorshapes.cpp
@@ -184,7 +184,7 @@ void bshape2(hpcshape& sh, PPR prio, int shapeid, matrixlist& m) {
       int mapped = 0;
       for(auto& m: matrices) {        
         hyperpoint z = m.first * h;
-        if(z[0] > -1e-5 && z[1] > -1e-5 && z[2] > -1e-5) {
+        if(z[0] > -1e-5 && z[1] > -1e-5 && z[GDIM] > -1e-5) {
           nh = m.second[r] * z, mapped++;
           }
         }
diff --git a/hyperpoint.cpp b/hyperpoint.cpp
index 57c0df5a..3bc302bf 100644
--- a/hyperpoint.cpp
+++ b/hyperpoint.cpp
@@ -427,11 +427,14 @@ void set_column(transmatrix& T, int i, const hyperpoint& H) {
   }
 
 transmatrix build_matrix(hyperpoint h1, hyperpoint h2, hyperpoint h3) {
-  transmatrix T = Id;
+  transmatrix T;
   for(int i=0; i<MDIM; i++)
     T[i][0] = h1[i],
     T[i][1] = h2[i],
     T[i][2] = h3[i];
+  if(DIM == 3) 
+    for(int i=0; i<MDIM; i++)
+      T[i][3] = (i == WDIM);
   return T;
   }