diff --git a/src/tools/qgepmaptooladdfeature.py b/src/tools/qgepmaptooladdfeature.py
index 9fa2d7b4..2ca5604b 100644
--- a/src/tools/qgepmaptooladdfeature.py
+++ b/src/tools/qgepmaptooladdfeature.py
@@ -334,9 +334,12 @@ def right_clicked(self, _):
                     # assign level if the match is a node or if we have 3D from snapping
                     if match.layer() == self.node_layer:
                         level = network_element['bottom_level']
+                        level = level if not math.isnan(level) else NULL
                         f.setAttribute(level_field_index, level)
                 elif self.rubberband.points[pt_idx].z() != 0:
-                    f.setAttribute(level_field_index, self.rubberband.points[pt_idx].z())
+                    level = self.rubberband.points[pt_idx].z()
+                    level = level if not math.isnan(level) else NULL
+                    f.setAttribute(level_field_index, level)
 
             dlg = self.iface.getFeatureForm(self.layer, f)
             dlg.setMode(QgsAttributeEditorContext.AddFeatureMode)