diff --git a/advlabdb/models.py b/advlabdb/models.py
index 9a34848..47d725c 100644
--- a/advlabdb/models.py
+++ b/advlabdb/models.py
@@ -113,7 +113,7 @@ class PartStudent(db.Model):
         Return True if final_part_mark changed, False otherwise.
         """
         finalWeightingSum = 0
-        finalMark = 0
+        finalMarkSum = 0
         groupExperiments = []
 
         for experimentMark in self.experiment_marks:
@@ -138,7 +138,11 @@ class PartStudent(db.Model):
             finalWeighting = semesterExperiment.final_weighting
             finalWeightingSum += finalWeighting
 
-            finalMark += finalWeighting * experimentMark.final_experiment_mark
+            # Not using final_experiment_mark to avoid rounding two times
+            finalMarkSum += finalWeighting * (
+                semesterExperiment.protocol_weighting * experimentMark.protocol_mark
+                + semesterExperiment.oral_weighting * experimentMark.oral_mark
+            )
 
         if set(groupExperiments) != set(self.group.group_experiments):
             flash(f"{self} does not have an experiment mark for every group experiment in his group!", "warning")
@@ -147,7 +151,7 @@ class PartStudent(db.Model):
         oldFinalPartMark = self.final_part_mark
 
         try:
-            self.final_part_mark = roundHalfUpToInt(finalMark / finalWeightingSum)
+            self.final_part_mark = roundHalfUpToInt(finalMarkSum / finalWeightingSum)
 
             db.session.commit()
         except Exception as ex: