diff --git a/cameo/ops.c b/cameo/ops.c
index 6457125..9b16ea8 100644
--- a/cameo/ops.c
+++ b/cameo/ops.c
@@ -1,8 +1,8 @@
 /*
  * ops.c - Higher-level toolpath operations
  *
- * Written 2010-2012 by Werner Almesberger
- * Copyright 2010-2012 Werner Almesberger
+ * Written 2010-2013 by Werner Almesberger
+ * Copyright 2010-2013 Werner Almesberger
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -49,6 +49,8 @@ struct path *tool_comp_paths(const struct path *paths, int dog_bone,
 	 * explicitly tell cameo to treat the path as an outside edge.
 	 */
 
+	if (!paths)
+		return NULL;
 	leftmost = path_find_leftmost(paths);
 	for (path = paths; path; path = path->next)
 		if (path != leftmost && (all_inside || !path->outside)) {