diff --git a/CHANGELOG.md b/CHANGELOG.md
index 9b8518d5..85f3e7d5 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -10,6 +10,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 ### Fixed
 
 - Allow iterators to go out of bounds with prev - [#587](https://github.com/PHPOffice/PhpSpreadsheet/issues/587)
+- Fix warning when reading xlsx without styles - [#631](https://github.com/PHPOffice/PhpSpreadsheet/pull/631)
 
 ## [1.4.0] - 2018-08-06
 
diff --git a/src/PhpSpreadsheet/Reader/Xlsx.php b/src/PhpSpreadsheet/Reader/Xlsx.php
index c6e8512d..a7709852 100644
--- a/src/PhpSpreadsheet/Reader/Xlsx.php
+++ b/src/PhpSpreadsheet/Reader/Xlsx.php
@@ -643,7 +643,7 @@ class Xlsx extends BaseReader
                             $excel->addCellXf($objStyle);
                         }
 
-                        foreach ($xmlStyles->cellStyleXfs->xf as $xf) {
+                        foreach (isset($xmlStyles->cellStyleXfs->xf) ? $xmlStyles->cellStyleXfs->xf : [] as $xf) {
                             $numFmt = NumberFormat::FORMAT_GENERAL;
                             if ($numFmts && $xf['numFmtId']) {
                                 $tmpNumFmt = self::getArrayItem($numFmts->xpath("sml:numFmt[@numFmtId=$xf[numFmtId]]"));