diff --git a/mc-edit-lines.el b/mc-edit-lines.el
index 3303620..20668cf 100644
--- a/mc-edit-lines.el
+++ b/mc-edit-lines.el
@@ -29,25 +29,62 @@
 
 (require 'multiple-cursors-core)
 
+(defcustom mc/edit-lines-empty-lines nil
+  "What should be done by `mc/edit-lines' when a line is not long enough."
+  :type '(radio (const :tag "Pad the line with spaces." pad)
+                (const :tag "Ignore the line." ignore)
+                (const :tag "Signal an error." error)
+                (const :tag "Nothing.  Cursor is at end of line." nil))
+  :group 'multiple-cursors)
+
 ;;;###autoload
-(defun mc/edit-lines ()
+(defun mc/edit-lines (&optional arg)
   "Add one cursor to each line of the active region.
 Starts from mark and moves in straight down or up towards the
-line point is on."
-  (interactive)
+line point is on.
+
+What is done with lines which are not long enough is governed by
+`mc/edit-lines-empty-lines'.  The prefix argument ARG can be used
+to override this.  If ARG is a symbol (when called from Lisp),
+that symbol is used instead of `mc/edit-lines-empty-lines'.
+Otherwise, if ARG negative, short lines will be ignored.  Any
+other non-nil value will cause short lines to be padded."
+  (interactive "P")
   (when (not (and mark-active (/= (point) (mark))))
-    (error "Mark a set of lines first."))
+    (error "Mark a set of lines first"))
   (mc/remove-fake-cursors)
   (let* ((col (current-column))
          (point-line (line-number-at-pos))
          (mark-line (progn (exchange-point-and-mark) (line-number-at-pos)))
-         (direction (if (< point-line mark-line) :up :down)))
+         (direction (if (< point-line mark-line) :up :down))
+         (style (cond
+                 ;; called from lisp
+                 ((and arg (symbolp arg))
+                  arg)
+                 ;; negative argument
+                 ((< (prefix-numeric-value arg) 0)
+                  'ignore)
+                 (arg 'pad)
+                 (t mc/edit-lines-empty-lines))))
     (deactivate-mark)
     (when (and (eq direction :up) (bolp))
       (previous-logical-line 1 nil)
       (move-to-column col))
+    ;; Add the cursors
     (while (not (eq (line-number-at-pos) point-line))
-      (mc/create-fake-cursor-at-point)
+      ;; Pad the line
+      (when (eq style 'pad)
+        (while (< (current-column) col)
+          (insert " ")))
+      ;; Error
+      (when (and (eq style 'error)
+                 (not (equal col (current-column))))
+        (error "Short line encountered in `mc/edit-lines'"))
+      ;; create the cursor
+      (unless (and (eq style 'ignore)
+                   (not (equal col (current-column))))
+        (mc/create-fake-cursor-at-point))
+      ;; proceed to next
       (if (eq direction :up)
           (previous-logical-line 1 nil)
         (next-logical-line 1 nil))