diff --git a/pupil_src/shared_modules/surface_tracker/surface.py b/pupil_src/shared_modules/surface_tracker/surface.py
index e3f2215b..3c7b4fa8 100644
--- a/pupil_src/shared_modules/surface_tracker/surface.py
+++ b/pupil_src/shared_modules/surface_tracker/surface.py
@@ -247,6 +247,9 @@ def map_gaze_and_fixation_events(self, events, camera_model, trans_matrix=None):
         results = []
         for event in events:
             gaze_norm_pos = event["norm_pos"]
+            if gaze_norm_pos is None:
+                continue
+
             gaze_img_point = methods.denormalize(
                 gaze_norm_pos, camera_model.resolution, flip_y=True
             )
@@ -270,7 +273,7 @@ def map_gaze_and_fixation_events(self, events, camera_model, trans_matrix=None):
                 copy_keys = ["id", "duration", "start timestamp [ns]", "end timestamp [ns]", "duration [ms]"]
             else:
                 copy_keys = ["confidence", "timestamp_unix"]
-            
+
             for key in copy_keys:
                 mapped_datum[key] = event[key]
 
diff --git a/pupil_src/shared_modules/surface_tracker/surface_tracker_offline.py b/pupil_src/shared_modules/surface_tracker/surface_tracker_offline.py
index 7d305558..6bafb5e8 100644
--- a/pupil_src/shared_modules/surface_tracker/surface_tracker_offline.py
+++ b/pupil_src/shared_modules/surface_tracker/surface_tracker_offline.py
@@ -592,11 +592,12 @@ def on_notify(self, notification):
             fixation_data = [datum.copy() for datum in self.g_pool.fixations]
 
             for fixation_event in fixation_data:
-                offset = self.get_gaze_offset_plugin().get_manual_correction_for_frame(fixation_event["mid_frame_index"])
-                fixation_event['norm_pos'] = (
-                    fixation_event['norm_pos'][0] + offset[0],
-                    fixation_event['norm_pos'][1] + offset[1],
-                )
+                if fixation_event['norm_pos'] is not None:
+                    offset = self.get_gaze_offset_plugin().get_manual_correction_for_frame(fixation_event["mid_frame_index"])
+                    fixation_event['norm_pos'] = (
+                        fixation_event['norm_pos'][0] + offset[0],
+                        fixation_event['norm_pos'][1] + offset[1],
+                    )
 
             corrected_fixations = pm.Affiliator(fixation_data, self.g_pool.fixations.data_ts, self.g_pool.fixations.stop_ts)