diff --git a/src/water.h b/src/water.h
index 8829d7700f..94a7db342b 100644
--- a/src/water.h
+++ b/src/water.h
@@ -27,7 +27,6 @@ FloodingBehaviour GetFloodingBehaviour(TileIndex tile);
 
 void TileLoop_Water(TileIndex tile);
 bool FloodHalftile(TileIndex t);
-void DoFloodTile(TileIndex target);
 
 void ConvertGroundTilesIntoWaterTiles();
 
@@ -38,7 +37,6 @@ void DrawShoreTile(Slope tileh);
 void MakeWaterKeepingClass(TileIndex tile, Owner o);
 void CheckForDockingTile(TileIndex t);
 
-bool RiverModifyDesertZone(TileIndex tile, void *data);
 void MakeRiverAndModifyDesertZoneAround(TileIndex tile);
 static const uint RIVER_OFFSET_DESERT_DISTANCE = 5; ///< Circular tile search radius to create non-desert around a river tile.
 
diff --git a/src/water_cmd.cpp b/src/water_cmd.cpp
index 099b05f25f..3e27379794 100644
--- a/src/water_cmd.cpp
+++ b/src/water_cmd.cpp
@@ -429,7 +429,7 @@ CommandCost CmdBuildLock(DoCommandFlag flags, TileIndex tile)
 }
 
 /** Callback to create non-desert around a river tile. */
-bool RiverModifyDesertZone(TileIndex tile, void *)
+static bool RiverModifyDesertZone(TileIndex tile, void *)
 {
 	if (GetTropicZone(tile) == TROPICZONE_DESERT) SetTropicZone(tile, TROPICZONE_NORMAL);
 	return false;
@@ -1114,7 +1114,7 @@ FloodingBehaviour GetFloodingBehaviour(TileIndex tile)
 /**
  * Floods a tile.
  */
-void DoFloodTile(TileIndex target)
+static void DoFloodTile(TileIndex target)
 {
 	assert(!IsTileType(target, MP_WATER));