--- a/src/PhysicsWorld.cc	Mon Dec 08 11:10:04 2008 +0000
+++ b/src/PhysicsWorld.cc	Mon Dec 08 12:02:20 2008 +0000
@@ -5,7 +5,11 @@
 #include <functional>
 
 PhysicsWorld::PhysicsWorld (Vector gravity, Vector dimensions) :
-    Terrain(dimensions.x, dimensions.y, 1337), tick_timer(PHYSICS_TICK_MS), dimensions(dimensions), gravity(gravity)
+    // XXX: assume Vector == PixelCoordinate
+    Terrain((unsigned int) dimensions.x, (unsigned int) dimensions.y, 1337), 
+    dimensions(dimensions), 
+    gravity(gravity),
+    tick_timer(PHYSICS_TICK_MS)
 {
     slots.connect(tick_timer.sig_tick(), this, &PhysicsWorld::tick);
     tick_timer.start();