diff --git a/src/tetris.c b/src/tetris.c
index 79e72e7..f826798 100644
--- a/src/tetris.c
+++ b/src/tetris.c
@@ -62,7 +62,11 @@ int tetris_intersect(const u8 *restrict const *restrict rows, u8 tetromino, uint
 	uint *pos = (uint[8]){x, y, x, y, x, y, x, y};
 	uint *end = pos + 8;
 	tetris_get_blocks(tetromino, pos);
-	while (pos < end && !rows[*(pos + 1)][*pos]) pos += 2;
+	for (; pos < end; pos += 2) {
+		if (*(pos + 0) >= TET_WIDTH) break;
+		if (*(pos + 1) >= TET_HEIGHT) break;
+		if (rows[*(pos + 1)][*pos]) break;
+	}
 	return pos < end;
 }