diff --git a/icartt/dataset.py b/icartt/dataset.py
index c239874bf425cafec731c9fa6ab1fe9d26d281bd..150451bfcc92a52838df3179b73a39d72e8c23d0 100644
--- a/icartt/dataset.py
+++ b/icartt/dataset.py
@@ -14,7 +14,7 @@ class Variable:
 class Dataset:
     @property
     def nheader(self):
-        total = 14 + self.ndvar + self.nscom + self.nncom
+        total = 12 + self.ndvar + 1 + self.nscom + 1 + self.nncom
         if self.format == 2110:
             total += self.nauxvar + 5
         return total