diff --git a/lib/FWIF/FWIF.php b/lib/FWIF/FWIF.php
index ae77074..60c40c9 100644
--- a/lib/FWIF/FWIF.php
+++ b/lib/FWIF/FWIF.php
@@ -239,7 +239,7 @@ class FWIF {
     }
 
     private const DATETIME_FLAG_TIME   = 0x40;
-    private const DATETIME_FLAG_MILLI  = 0x20;
+    private const DATETIME_FLAG_MILLI  = 0x4000;
 
     private const DATETIME_YEAR_SIGN  = 0x40000000;
     private const DATETIME_YEAR_MASK  = 0x3FFF;
@@ -265,9 +265,9 @@ class FWIF {
 
     /* +--------+--------+
      * |.YYYYYYY|YYYYYYYY|
-     * |MMMMDDDD|DTVHHHHH|
-     * |..mmmmmm|SSSSSSvv|
-     * |vvvvvvvv|        |
+     * |MMMMDDDD|DT.HHHHH|
+     * |.Wmmmmmm|SSSSSSww|
+     * |wwwwwwww|        |
      * +--------+--------+
      */
 
@@ -300,32 +300,32 @@ class FWIF {
 
         if($mins > 0 || $secs > 0 || $millis > 0) {
             $ymdfh |= self::DATETIME_FLAG_TIME;
-            $msv    = 0;
-            $msv   |= ($mins  & self::DATETIME_MINS_MASK) << self::DATETIME_MINS_SHIFT;
-            $msv   |= ($secs  & self::DATETIME_SECS_MASK) << self::DATETIME_SECS_SHIFT;
+            $msw    = 0;
+            $msw   |= ($mins  & self::DATETIME_MINS_MASK) << self::DATETIME_MINS_SHIFT;
+            $msw   |= ($secs  & self::DATETIME_SECS_MASK) << self::DATETIME_SECS_SHIFT;
 
             if($millis > 0) {
-                $ymdfh |=  self::DATETIME_FLAG_MILLI;
-                $msv   |= ($millis & self::DATETIME_MILLI_HI_MASK) >> self::DATETIME_MILLI_HI_SHIFT;
-                $v      =  $millis & self::DATETIME_MILLI_LO_MASK;
+                $msw |=  self::DATETIME_FLAG_MILLI;
+                $msw |= ($millis & self::DATETIME_MILLI_HI_MASK) >> self::DATETIME_MILLI_HI_SHIFT;
+                $w    =  $millis & self::DATETIME_MILLI_LO_MASK;
             }
         }
 
         $packed = pack('N', $ymdfh);
         if($ymdfh & self::DATETIME_FLAG_TIME) {
-            $packed .= pack('n', $msv);
-            if($ymdfh & self::DATETIME_FLAG_MILLI)
-                $packed .= chr($v);
+            $packed .= pack('n', $msw);
+            if($msw & self::DATETIME_FLAG_MILLI)
+                $packed .= chr($w);
         }
 
         return $packed;
     }
     private static function decodeDateTime($data, int $flags): DateTimeInterface {
         $ymdfh  = unpack('N', fread($data, 4))[1];
-        $hasMsv = $ymdfh & self::DATETIME_FLAG_TIME;
-        $hasV   = $hasMsv && ($ymdfh & self::DATETIME_FLAG_MILLI);
-        $msv    = $hasMsv ? unpack('n', fread($data, 2))[1] : 0;
-        $v      = $hasV   ? ord(fgetc($data)) : 0;
+        $hasMsw = $ymdfh & self::DATETIME_FLAG_TIME;
+        $msw    = $hasMsw ? unpack('n', fread($data, 2))[1] : 0;
+        $hasW   = $hasMsw && ($msw & self::DATETIME_FLAG_MILLI);
+        $w      = $hasW   ? ord(fgetc($data)) : 0;
 
         $year  = ($ymdfh >> self::DATETIME_YEAR_SHIFT)  & self::DATETIME_YEAR_MASK;
         $month = ($ymdfh >> self::DATETIME_MONTH_SHIFT) & self::DATETIME_MONTH_MASK;
@@ -336,13 +336,13 @@ class FWIF {
             $year = ~$year;
         $dt = sprintf('%04d-%02d-%02dT%02d:', $year, $month, $day, $hour);
 
-        if($hasMsv) {
-            $mins = ($msv >> self::DATETIME_MINS_SHIFT) & self::DATETIME_MINS_MASK;
-            $secs = ($msv >> self::DATETIME_SECS_SHIFT) & self::DATETIME_SECS_MASK;
+        if($hasMsw) {
+            $mins = ($msw >> self::DATETIME_MINS_SHIFT) & self::DATETIME_MINS_MASK;
+            $secs = ($msw >> self::DATETIME_SECS_SHIFT) & self::DATETIME_SECS_MASK;
             $dt  .= sprintf('%02d:%02d', $mins, $secs);
             if($hasV) {
-                $millis  = ($msv << self::DATETIME_MILLI_HI_SHIFT) & self::DATETIME_MILLI_HI_MASK;
-                $millis |=  $v;
+                $millis  = ($msw << self::DATETIME_MILLI_HI_SHIFT) & self::DATETIME_MILLI_HI_MASK;
+                $millis |=  $w;
                 $dt .= sprintf('.%03d', $millis);
             }
         } else $dt .= '00:00';