diff --git a/prelude.ld b/prelude.ld
index c70f607..b6b0c3d 100644
--- a/prelude.ld
+++ b/prelude.ld
@@ -1271,7 +1271,7 @@ fn heading/vector {
 fn apply_command {
 	"Takes a turtle state and a command and calculates a new state."
 	(state, command) -> match command with {
-		(:goto, (x, y)) -> assoc (state, :position, (x, y))
+		(:goto, (x, y)) -> assoc (state, :position, (neg (x), y))
 		(:home) -> assoc (state, :position, (0, 0))
 		(:clear) -> assoc (state, :position, (0, 0))
 		(:right, turns) -> update (state, :heading, add (_, turns))