diff --git a/CHANGELOG.md b/CHANGELOG.md
index b3dd17a4da..a3f149df2a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -26,6 +26,7 @@ and this project adheres to [Semantic Versioning](https://semver.org).
 ### Fixed
 
 - Ensure that the list of shared formulae is maintained when an xlsx file is chunked with readFilter[Issue #169](https://github.com/PHPOffice/PhpSpreadsheet/issues/1669).
+- Fix for notice during accessing "cached magnification factor" offset [#1354](https://github.com/PHPOffice/PhpSpreadsheet/pull/1354)
 
 ## 1.15.0 - 2020-10-11
 
diff --git a/src/PhpSpreadsheet/Reader/Xls.php b/src/PhpSpreadsheet/Reader/Xls.php
index 81cc5b2eda..b5c92d8d2a 100644
--- a/src/PhpSpreadsheet/Reader/Xls.php
+++ b/src/PhpSpreadsheet/Reader/Xls.php
@@ -4377,11 +4377,22 @@ private function readWindow2(): void
             // offset: 10; size: 2; cached magnification factor in page break preview (in percent); 0 = Default (60%)
             // offset: 12; size: 2; cached magnification factor in normal view (in percent); 0 = Default (100%)
             // offset: 14; size: 4; not used
-            $zoomscaleInPageBreakPreview = self::getUInt2d($recordData, 10);
+            if (!isset($recordData[10])) {
+                $zoomscaleInPageBreakPreview = 0;
+            } else {
+                $zoomscaleInPageBreakPreview = self::getUInt2d($recordData, 10);
+            }
+
             if ($zoomscaleInPageBreakPreview === 0) {
                 $zoomscaleInPageBreakPreview = 60;
             }
-            $zoomscaleInNormalView = self::getUInt2d($recordData, 12);
+
+            if (!isset($recordData[12])) {
+                $zoomscaleInNormalView = 0;
+            } else {
+                $zoomscaleInNormalView = self::getUInt2d($recordData, 12);
+            }
+
             if ($zoomscaleInNormalView === 0) {
                 $zoomscaleInNormalView = 100;
             }