diff --git a/src/gui_qt/io/dscreader.py b/src/gui_qt/io/dscreader.py
index 33f7938..c9fb6a3 100644
--- a/src/gui_qt/io/dscreader.py
+++ b/src/gui_qt/io/dscreader.py
@@ -195,7 +195,11 @@ class QDSCReader(QtWidgets.QDialog, Ui_Dialog):
     @QtCore.pyqtSlot(QtWidgets.QAbstractButton, name='on_buttonGroup_buttonClicked')
     @QtCore.pyqtSlot(int, name='on_cp_checkBox_stateChanged')
     def update_plots(self, _=None):
-        sample_data, raw_sample, empty_data, drift_value, slope, calib_x, calib_y, regions = self.get_data()
+        res = self.get_data()
+        if res is None:
+            return
+
+        sample_data, raw_sample, empty_data, drift_value, slope, calib_x, calib_y, regions = res
 
         self.raw_sample.setData(x=raw_sample[0], y=raw_sample[1])
         self.drift_sample.setData(x=drift_value[0], y=drift_value[1])
diff --git a/src/nmreval/io/dsc.py b/src/nmreval/io/dsc.py
index 797714c..84c024f 100644
--- a/src/nmreval/io/dsc.py
+++ b/src/nmreval/io/dsc.py
@@ -284,6 +284,7 @@ class DSCCalibrator:
 
         sample_data[1] -= empty_y
         drift_value = sample_data.copy()[(2, 1), :]
+        sample_data = sample_data[:, np.isfinite(sample_data[1, :])]
 
         mean_isotherms = []
         for offset in [-1, 1]:
@@ -311,6 +312,8 @@ class DSCCalibrator:
                 # calculate mean slope of heat flow from points in the beginning
                 offset = sample_data[1, 200]
                 grad = np.gradient(sample_data[1, :], sample_data[2, :])
+
+                grad = grad[~np.isnan(grad)]
                 m = grad[(grad < grad.mean()+grad.std()/5)*(grad > grad.mean()-grad.std()/5)].mean()
 
             sample_data[1] -= m * (sample_data[2] - sample_data[2, 200]) + offset