diff --git a/src/app/[lang]/(mods-pages)/student/grades/GradesViewer.tsx b/src/app/[lang]/(mods-pages)/student/grades/GradesViewer.tsx
index cdee1927..94b12404 100644
--- a/src/app/[lang]/(mods-pages)/student/grades/GradesViewer.tsx
+++ b/src/app/[lang]/(mods-pages)/student/grades/GradesViewer.tsx
@@ -127,13 +127,14 @@ const GradesViewer = ({ grades }: { grades: GradeObject }) => {
 
     // get unique semesters
     const semesters = Array.from(new Set(grades.ranking.data.map(grade => grade.year + grade.semester))).toReversed();
-
+    // grades might have semesters that are not in ranking
+    const gradesSemesters = Array.from(new Set(grades.grades.map(grade => grade.year + grade.semester))).toReversed();
     const displayGrades = grades.grades.filter(grade => {
-        if (selectedSemester == "All") return semesters.includes(grade.year + grade.semester);
+        if (selectedSemester == "All") return true;
         return grade.year + grade.semester == selectedSemester;
     });
 
-    const displayedSemesters = semesters.filter(semester => {
+    const displayedSemesters = gradesSemesters.filter(semester => {
         if (selectedSemester == "All") return true;
         return semester == selectedSemester;
     });
@@ -175,7 +176,7 @@ const GradesViewer = ({ grades }: { grades: GradeObject }) => {
                     </SelectTrigger>
                     <SelectContent >
                         <SelectItem value={"All"}>全部課程</SelectItem>
-                        {semesters.map(sem_id => <SelectItem key={sem_id} value={sem_id}>{toPrettySemester(sem_id)}</SelectItem>)}
+                        {gradesSemesters.map(sem_id => <SelectItem key={sem_id} value={sem_id}>{toPrettySemester(sem_id)}</SelectItem>)}
                     </SelectContent>
                 </Select>}
                 {tab == "semester" && <Select value={semesterSort} onValueChange={(e: string) => setSemesterSort(e as "asc" | "desc")}>