--- a/src/oldloader.cpp	Tue May 13 10:17:04 2008 +0000
+++ b/src/oldloader.cpp	Tue May 13 12:15:52 2008 +0000
@@ -1664,7 +1664,13 @@
 				 * clear it for ourselves and let OTTD's rebuild PBS itself */
 				_m[i].m4 &= 0xF; /* Only keep the lower four bits; upper four is PBS */
 				break;
-			default: break;
+
+			case MP_WATER:
+				if (GetWaterClass(i) == 3) MakeRiver(i, Random());
+				break;
+
+			default:
+				break;
 		}
 	}
 

--- a/src/openttd.cpp	Tue May 13 10:17:04 2008 +0000
+++ b/src/openttd.cpp	Tue May 13 12:15:52 2008 +0000
@@ -2425,9 +2425,7 @@
 
 			/* Move river flag and update canals to use water class */
 			if (IsTileType(t, MP_WATER)) {
-				if (_m[t].m5 == 2) {
-					MakeRiver(t, Random());
-				} else {
+				if (GetWaterClass(t) != WATER_CLASS_RIVER) {
 					if (IsWater(t)) {
 						Owner o = GetTileOwner(t);
 						if (o == OWNER_WATER) {