diff --git a/pmc/cube.cc b/pmc/cube.cc
--- a/pmc/cube.cc
+++ b/pmc/cube.cc
@@ -22,10 +22,11 @@
     height = 25;
 }
 
-Cube::Cube (Surface * s, Vector p1, Vector p2, Vector p3, Vector p4, int h)
+Cube::Cube (Surface * s, Vector& p1, Vector& p2, Vector& p3, Vector& p4, int h)
 {
     height = h;
     surface = s;
+    Vector location(h/2, h/2);
 
     P[0] = new Vector (p1);
     P[1] = new Vector (p2);
@@ -34,13 +35,13 @@
 
     for (int i = 0; i < 4; i++) {
         P[4 + i] = new Vector (*P[i]);
-        *P[4 + i] = *P[i] + Vector (h / 2, h / 2);
+        *P[4 + i] = *P[i] + location;
     }
 }
 
 Cube::~Cube ()
 {
-    for (int i = 0; i < 6; i++) {
+    for (int i = 0; i < 8; i++) {
 #ifdef DEBUG
         fprintf (stderr, "Removing P[%d]: ", i);
 #endif