diff --git a/src/PhpSpreadsheet/Reader/Excel2003XML.php b/src/PhpSpreadsheet/Reader/Excel2003XML.php
index 8e9f82f4..f74e513a 100644
--- a/src/PhpSpreadsheet/Reader/Excel2003XML.php
+++ b/src/PhpSpreadsheet/Reader/Excel2003XML.php
@@ -479,7 +479,7 @@ class Excel2003XML extends BaseReader implements IReader
                                     $this->styles[$styleID]['fill']['color']['rgb'] = substr($styleAttributeValue, 1);
                                     break;
                                 case 'Pattern':
-                                    $this->styles[$styleID]['fill']['type'] = substr($styleAttributeValue, 1);
+                                    $this->styles[$styleID]['fill']['type'] = strtolower($styleAttributeValue);
                                     break;
                             }
                         }