diff --git a/lib/FileAPI.XHR.js b/lib/FileAPI.XHR.js
index d08d54e4..0787896b 100644
--- a/lib/FileAPI.XHR.js
+++ b/lib/FileAPI.XHR.js
@@ -128,6 +128,10 @@
 			}
 			else {
 				// html5
+				if (this.xhr && this.xhr.aborted) {
+					api.log("Error: already aborted");
+					return;
+				}
 				xhr = _this.xhr = api.getXHR();
 
 				if (data.params) {
@@ -223,7 +227,7 @@
 					};
 
 					data.start = data.end + 1;
-					data.end = Math.min(data.start + options.chunkSize, data.size ) - 1;
+					data.end = Math.max(Math.min(data.start + options.chunkSize, data.size ) - 1, data.start);
                     
 					var slice;
 					(slice = 'slice') in data.file || (slice = 'mozSlice') in data.file || (slice = 'webkitSlice') in data.file;