diff --git a/Classes/PHPExcel/Style/NumberFormat.php b/Classes/PHPExcel/Style/NumberFormat.php
index 39e5dfab..62ab3e27 100644
--- a/Classes/PHPExcel/Style/NumberFormat.php
+++ b/Classes/PHPExcel/Style/NumberFormat.php
@@ -505,8 +505,8 @@ class PHPExcel_Style_NumberFormat extends PHPExcel_Style_Supervisor implements P
 			$numbers = explode('.', $number . '.0');
 			$masks = explode('.', $mask . '.0');
 			$result1 = self::_complexNumberFormatMask($numbers[0], $masks[0], 1);
-			$result2 = strrev(self::_complexNumberFormatMask(strrev($numbers[1]), strrev($masks[1])), 1);
-			return $result1 . '.' . $result2;
+			$result2 = strrev(self::_complexNumberFormatMask(strrev($numbers[1]), strrev($masks[1]), 1));
+			return (($sign) ? '-' : '') . $result1 . '.' . $result2;
 		}
 
 		$r = preg_match_all('/0+/', $mask, $result, PREG_OFFSET_CAPTURE);
diff --git a/unitTests/rawTestData/Style/NumberFormat.data b/unitTests/rawTestData/Style/NumberFormat.data
index 08a0d6a7..49acaccf 100644
--- a/unitTests/rawTestData/Style/NumberFormat.data
+++ b/unitTests/rawTestData/Style/NumberFormat.data
@@ -33,3 +33,5 @@
 123456789,	'0 (+00) 0000 00 00 00',				"0 (+00) 0123 45 67 89"
 123456789,	'0000:00:00',							"12345:67:89"
 -123456789,	'0000:00:00',							"-12345:67:89"
+1234567.89,	'0000:00.00',							"12345:67.89"
+-1234567.89,'0000:00.00',							"-12345:67.89"