diff --git a/data/maproombuilder.lua b/data/maproombuilder.lua
index 6be0406..f020d95 100644
--- a/data/maproombuilder.lua
+++ b/data/maproombuilder.lua
@@ -373,7 +373,8 @@ function module.build_square_room(map, room)
 	end
 
 	if CURRENT_LEVEL > 2 and random(10) == 1 then
-		set_modifier(map, "WINDY");
+		directions = { "LEFT", "RIGHT", "UP", "DOWN" }
+		set_modifier(map, "WINDY", directions[random(#directions)]);
 	end
 end
 
diff --git a/src/map_lua.c b/src/map_lua.c
index 713b015..47928f4 100644
--- a/src/map_lua.c
+++ b/src/map_lua.c
@@ -92,15 +92,26 @@ SDL_Renderer* luaL_checksdlrenderer(lua_State *L)
 static int
 l_map_set_current_room_modifier(lua_State *L)
 {
-	const char *modifier;
+	const char *modifier, *direction;
 
 	Map *map = luaL_checkmap(L, 1);
 	modifier = luaL_checkstring(L, 2);
+	direction = luaL_checkstring(L, 3);
+
+	Vector2d dir = VECTOR2D_LEFT;
+	if (strcmp(direction, "LEFT") == 0)
+		dir = VECTOR2D_LEFT;
+	else if (strcmp(direction, "RIGHT") == 0)
+		dir = VECTOR2D_RIGHT;
+	else if (strcmp(direction, "UP") == 0)
+		dir = VECTOR2D_UP;
+	else if (strcmp(direction, "DOWN") == 0)
+		dir = VECTOR2D_DOWN;
 
 	if (strcmp(modifier, "WINDY") == 0) {
 		Room *room = map->rooms[map->currentRoom.x][map->currentRoom.y];
 		room->modifier.type = RMOD_TYPE_WINDY;
-		room->modifier.data.wind.direction = VECTOR2D_LEFT;
+		room->modifier.data.wind.direction = dir;
 	} else {
 		luaL_error(L, "Unknown room modifier: %s", modifier);
 		return 1;
diff --git a/src/vector2d.c b/src/vector2d.c
index 9063577..7b711a3 100644
--- a/src/vector2d.c
+++ b/src/vector2d.c
@@ -9,5 +9,6 @@ vector2d_equals(Vector2d v1, Vector2d v2)
 bool
 vector2d_is_opposite(Vector2d v1, Vector2d v2)
 {
-	return (v1.x > 0 && v2.x < 0) ^ (v1.y > 0 && v2.y < 0);
+	return ((v1.x > 0 && v2.x < 0) ^ (v1.y > 0 && v2.y < 0))
+		|| ((v1.x < 0 && v2.x > 0) ^ (v1.y < 0 && v2.y > 0));
 }