diff --git a/phpseclib/File/ANSI.php b/phpseclib/File/ANSI.php
index 0f1990d4..07624d60 100644
--- a/phpseclib/File/ANSI.php
+++ b/phpseclib/File/ANSI.php
@@ -305,6 +305,9 @@ class ANSI
                             case preg_match('#\x1B\[(\d+)D#', $this->ansi, $match): // Move cursor left n lines
                                 $this->old_x = $this->x;
                                 $this->x-= $match[1];
+                                if ($this->x < 0) {
+                                    $this->x = 0;
+                                }
                                 break;
                             case preg_match('#\x1B\[(\d+);(\d+)r#', $this->ansi, $match): // Set top and bottom lines of a window
                                 break;