--- a/src/town_cmd.cpp	Mon Apr 21 13:45:03 2008 +0000
+++ b/src/town_cmd.cpp	Mon Apr 21 14:33:33 2008 +0000
@@ -1936,7 +1936,7 @@
 
 			if (HasBit(hs->callback_mask, CBM_HOUSE_ALLOW_CONSTRUCTION)) {
 				uint16 callback_res = GetHouseCallback(CBID_HOUSE_ALLOW_CONSTRUCTION, 0, 0, house, t, tile);
-				if (callback_res != CALLBACK_FAILED && callback_res == 0) continue;
+				if (callback_res != CALLBACK_FAILED && GB(callback_res, 0, 8) == 0) continue;
 			}
 		}