diff --git a/src/Elm/Kernel/File.js b/src/Elm/Kernel/File.js
index 5bcd3ad..9186d8e 100755
--- a/src/Elm/Kernel/File.js
+++ b/src/Elm/Kernel/File.js
@@ -29,7 +29,8 @@ function _File_size(file) { return file.size; }
 
 function _File_lastModified(file)
 {
-	return __Time_millisToPosix(file.lastModified);
+	// IE10 and IE11 don't support lastModified, but have lastModifiedDate
+	return __Time_millisToPosix(file.lastModified || file.lastModifiedDate);
 }