diff --git a/src/lang/english.txt b/src/lang/english.txt
index d0218c1ecc..be9f8a9884 100644
--- a/src/lang/english.txt
+++ b/src/lang/english.txt
@@ -5105,6 +5105,7 @@ STR_ERROR_ALREADY_AT_SEA_LEVEL                                  :{WHITE}... alre
 STR_ERROR_TOO_HIGH                                              :{WHITE}... too high
 STR_ERROR_ALREADY_LEVELLED                                      :{WHITE}... already flat
 STR_ERROR_BRIDGE_TOO_HIGH_AFTER_LOWER_LAND                      :{WHITE}Afterwards the bridge above it would be too high.
+STR_ERROR_MUST_DEMOLISH_RIVER_FIRST                             :{WHITE}Must demolish river first
 
 # Company related errors
 STR_ERROR_CAN_T_CHANGE_COMPANY_NAME                             :{WHITE}Can't change company name...
diff --git a/src/script/api/script_error.hpp b/src/script/api/script_error.hpp
index 61961f13ec..e6346c9ce6 100644
--- a/src/script/api/script_error.hpp
+++ b/src/script/api/script_error.hpp
@@ -150,7 +150,7 @@ public:
 		ERR_ALREADY_BUILT,                            // [STR_ERROR_ALREADY_BUILT, STR_ERROR_MUST_DEMOLISH_BRIDGE_FIRST, STR_ERROR_TREE_ALREADY_HERE]
 
 		/** Area isn't clear, try to demolish the building on it */
-		ERR_AREA_NOT_CLEAR,                           // [STR_ERROR_BUILDING_MUST_BE_DEMOLISHED, STR_ERROR_MUST_DEMOLISH_BRIDGE_FIRST, STR_ERROR_MUST_DEMOLISH_RAILROAD, STR_ERROR_MUST_DEMOLISH_AIRPORT_FIRST, STR_ERROR_MUST_DEMOLISH_CARGO_TRAM_STATION_FIRST, STR_ERROR_MUST_DEMOLISH_TRUCK_STATION_FIRST, STR_ERROR_MUST_DEMOLISH_PASSENGER_TRAM_STATION_FIRST, STR_ERROR_MUST_DEMOLISH_BUS_STATION_FIRST, STR_ERROR_BUOY_IN_THE_WAY, STR_ERROR_MUST_DEMOLISH_DOCK_FIRST, STR_ERROR_GENERIC_OBJECT_IN_THE_WAY, STR_ERROR_COMPANY_HEADQUARTERS_IN, STR_ERROR_OBJECT_IN_THE_WAY, STR_ERROR_MUST_REMOVE_ROAD_FIRST, STR_ERROR_MUST_REMOVE_RAILROAD_TRACK, STR_ERROR_MUST_DEMOLISH_BRIDGE_FIRST, STR_ERROR_MUST_DEMOLISH_TUNNEL_FIRST, STR_ERROR_EXCAVATION_WOULD_DAMAGE, STR_ERROR_MUST_DEMOLISH_CANAL_FIRST, STR_ERROR_MUST_REMOVE_RAILWAY_STATION_FIRST, STR_ERROR_MUST_REMOVE_ROAD_STOP_FIRST, STR_ERROR_MUST_REMOVE_SIGNALS_FIRST]
+		ERR_AREA_NOT_CLEAR,                           // [STR_ERROR_BUILDING_MUST_BE_DEMOLISHED, STR_ERROR_MUST_DEMOLISH_BRIDGE_FIRST, STR_ERROR_MUST_DEMOLISH_RAILROAD, STR_ERROR_MUST_DEMOLISH_AIRPORT_FIRST, STR_ERROR_MUST_DEMOLISH_CARGO_TRAM_STATION_FIRST, STR_ERROR_MUST_DEMOLISH_TRUCK_STATION_FIRST, STR_ERROR_MUST_DEMOLISH_PASSENGER_TRAM_STATION_FIRST, STR_ERROR_MUST_DEMOLISH_BUS_STATION_FIRST, STR_ERROR_BUOY_IN_THE_WAY, STR_ERROR_MUST_DEMOLISH_DOCK_FIRST, STR_ERROR_GENERIC_OBJECT_IN_THE_WAY, STR_ERROR_COMPANY_HEADQUARTERS_IN, STR_ERROR_OBJECT_IN_THE_WAY, STR_ERROR_MUST_REMOVE_ROAD_FIRST, STR_ERROR_MUST_REMOVE_RAILROAD_TRACK, STR_ERROR_MUST_DEMOLISH_BRIDGE_FIRST, STR_ERROR_MUST_DEMOLISH_TUNNEL_FIRST, STR_ERROR_EXCAVATION_WOULD_DAMAGE, STR_ERROR_MUST_DEMOLISH_CANAL_FIRST, STR_ERROR_MUST_REMOVE_RAILWAY_STATION_FIRST, STR_ERROR_MUST_REMOVE_ROAD_STOP_FIRST, STR_ERROR_MUST_REMOVE_SIGNALS_FIRST, STR_ERROR_MUST_DEMOLISH_RIVER_FIRST]
 
 		/** Area / property is owned by another company */
 		ERR_OWNED_BY_ANOTHER_COMPANY,                 // [STR_ERROR_AREA_IS_OWNED_BY_ANOTHER, STR_ERROR_OWNED_BY]
diff --git a/src/water_cmd.cpp b/src/water_cmd.cpp
index 5a469f0f0a..0565ecb61b 100644
--- a/src/water_cmd.cpp
+++ b/src/water_cmd.cpp
@@ -1449,6 +1449,9 @@ static CommandCost TerraformTile_Water(TileIndex tile, DoCommandFlags flags, int
 	/* Canals can't be terraformed */
 	if (IsWaterTile(tile) && IsCanal(tile)) return CommandCost(STR_ERROR_MUST_DEMOLISH_CANAL_FIRST);
 
+	/* Rivers can't be terraformed */
+	if (IsWaterTile(tile) && IsRiver(tile)) return CommandCost(STR_ERROR_MUST_DEMOLISH_RIVER_FIRST);
+
 	return Command<Commands::LandscapeClear>::Do(flags, tile);
 }