diff --git a/uckf.go b/uckf.go
index 97981a1..7b62c0a 100644
--- a/uckf.go
+++ b/uckf.go
@@ -56,7 +56,7 @@ func main() {
 }
 
 func onBoard(i, j int) bool {
-	return i > 0 && j > 0 && i < *edgeSize && j < *edgeSize
+	return i >= 0 && j >= 0 && i < *edgeSize && j < *edgeSize
 }
 func charAt(board [][]byte, i, j int) byte {
 	if !onBoard(i, j) {