diff --git a/lib/lib/monitor_file.js b/lib/lib/monitor_file.js
index a6249de..cd06832 100644
--- a/lib/lib/monitor_file.js
+++ b/lib/lib/monitor_file.js
@@ -114,7 +114,7 @@ MonitoredFile.prototype.restart = function(start_index) {
             if (err) {
               return this.emit('error', err);
             }
-            if (file_status[this.filename]) {
+            if (file_status[this.filename] && file_status[this.filename].last_data && file_status[this.filename].index) {
               var last_data = file_status[this.filename].last_data;
               if (file_status[this.filename].index >= last_data.length && stats.size > last_data.length) {
                 var buffer =  new Buffer(last_data.length);