diff -r b862a4add8b0 -r 8bea44dae56f src/openttd.cpp
--- a/src/openttd.cpp	Tue May 20 20:03:45 2008 +0000
+++ b/src/openttd.cpp	Tue May 20 20:14:34 2008 +0000
@@ -2336,9 +2336,7 @@
 
 			/* 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) {