diff --git a/src/icartt/dataset.py b/src/icartt/dataset.py
index 840bce08dd6e18efb3428536a0aa3e6e74b6c04c..418073d89daaebe0e5dd096a9e12a944b4155719 100644
--- a/src/icartt/dataset.py
+++ b/src/icartt/dataset.py
@@ -461,20 +461,12 @@ class Dataset:
                     dmp = [word.strip(" ") for word in dmp.split(self.splitChar)]
                 return dmp
 
-        if self.inputFhandle.closed:
-            self.inputFhandle = open(self.inputFhandle.name, encoding='utf-8')
+        if self.inputFhandle:
+            if self.inputFhandle.closed:
+                self.inputFhandle = open(self.inputFhandle.name, encoding='utf-8')
 
-        # TODO: refactor following try/except statement
-        # this one is challenging since we need an "unpopulated" file pointer if no file was specified :)
-        try:
             f = FilehandleWithLinecounter(self.inputFhandle, splitChar)
-
             self._readHeader(f)
-
-            del f
-        except:
-            a = 1
-        finally:
             self.inputFhandle.close()
 
     def _readHeader(self, f):
@@ -923,6 +915,8 @@ class Dataset:
 
         self.defineMode = True
 
+        self.inputFhandle = None
+
         # read data if f is not None
         if f is not None:
             if isinstance(f, (str, pathlib.Path)):