diff --git a/Classes/PHPExcel/Reader/Gnumeric.php b/Classes/PHPExcel/Reader/Gnumeric.php
index 50e7a8a..9e2b241 100644
--- a/Classes/PHPExcel/Reader/Gnumeric.php
+++ b/Classes/PHPExcel/Reader/Gnumeric.php
@@ -511,7 +511,7 @@ class PHPExcel_Reader_Gnumeric extends PHPExcel_Reader_Abstract implements PHPEx
 
 					//	We still set the number format mask for date/time values, even if _readDataOnly is true
 					if ((!$this->_readDataOnly) ||
-						(PHPExcel_Shared_Date::isDateTimeFormatCode($styleArray['numberformat']['code']))) {
+						(PHPExcel_Shared_Date::isDateTimeFormatCode((string) $styleAttributes['Format']))) {
 						$styleArray = array();
 						$styleArray['numberformat']['code'] = (string) $styleAttributes['Format'];
 						//	If _readDataOnly is false, we set all formatting information
diff --git a/changelog.txt b/changelog.txt
index 13b7964..17b8281 100644
--- a/changelog.txt
+++ b/changelog.txt
@@ -36,6 +36,7 @@ Fixed in develop branch for release v1.8.0:
                                                   Fix also applied to duplicating conditional styles
 - Bugfix:   (IndrekHaav)      Work Item GH-212  - Fix for formulae that reference a sheet whose name begins with a digit:
                                                   these were erroneously identified as numeric values, causing the parser to throw an undefined variable error.
+- Bugfix:   (IndrekHaav)      Work Item CP16208 - Fixed undefined variable error due to $styleArray being used before it's initialised
 - Feature:  (amerov)                            - Implementation of the Excel HLOOKUP() function
 - Feature:  (MBaker)                            - Added "Quote Prefix" to style settings (Excel2007 Reader and Writer only)
 - Feature:  (MBaker)                            - Added Horizontal FILL alignment for Excel5 and Excel2007 Readers/Writers, and Horizontal DISTRIBUTED alignment for Excel2007 Reader/Writer