diff --git a/src/icartt/dataset.py b/src/icartt/dataset.py
index b00c338b16c52a58ec56c05dca645a45955b4a3e..df697872d5b5c2437eca8da2877dfcbfecdf9cec 100644
--- a/src/icartt/dataset.py
+++ b/src/icartt/dataset.py
@@ -71,7 +71,7 @@ class DataStore1001:
             if key in self.varnames:
                 newline[key] = vmiss_to_npnan(kwargs[key], self.missvals[key])
 
-        if type(self.data) is type(None): # TODO: None is the sole instance of None ;-) => can use "if self.data is None"
+        if self.data is None:
             self.data = newline
             self.data = self.data.reshape(1)  # don't even ask
         else: