diff --git a/src/gui_qt/graphs/graphwindow.py b/src/gui_qt/graphs/graphwindow.py
index 61f318c..7796b81 100644
--- a/src/gui_qt/graphs/graphwindow.py
+++ b/src/gui_qt/graphs/graphwindow.py
@@ -4,7 +4,7 @@ import itertools
 import os
 import uuid
 
-from math import isnan
+from math import isfinite
 from pathlib import Path
 
 import numpy as np
@@ -493,9 +493,9 @@ class QGraphWindow(QtWidgets.QGraphicsView, Ui_GraphWindow):
                 with errstate(all='ignore'):
                     xy = [log10(val) for val in xy]
 
-                if isnan(xy[1]):
+                if not isfinite(xy[1]):
                     xy = [-1, 1]
-                elif isnan(xy[0]):
+                elif not isfinite(xy[0]):
                     xy[0] = xy[1]-4
 
             func(xy[0], xy[1], padding=0)