diff --git a/services/frontend/src/components/CustomPopulation/CourseMatrixExport.tsx b/services/frontend/src/components/CustomPopulation/CourseMatrixExport.tsx
index 7bb6e8750..99ee91d0c 100644
--- a/services/frontend/src/components/CustomPopulation/CourseMatrixExport.tsx
+++ b/services/frontend/src/components/CustomPopulation/CourseMatrixExport.tsx
@@ -20,10 +20,10 @@ export const CourseMatrixExport = ({
   const { getTextIn } = useLanguage()
 
   const getXlsx = () => {
-    const courseInfoById = new Map(
-      courses.map(({ course }) => [course.id, { code: course.code, name: getTextIn(course.name) ?? '' }])
+    const courseInfoByGroupId = new Map(
+      courses.map(({ course }) => [course.groupId, { code: course.code, name: getTextIn(course.name) ?? '' }])
     )
-    const { completedCoursesRows, courseCounterRows } = calculateExcelData(students, courseInfoById)
+    const { completedCoursesRows, courseCounterRows } = calculateExcelData(students, courseInfoByGroupId)
 
     // Columns: Student number, Name, student's attainments in the format: "course name (course code)"
     const completedCoursesSheet = utils.aoa_to_sheet([['Student number', 'Name'], ...completedCoursesRows])
diff --git a/services/frontend/src/components/CustomPopulation/courseMatrix.ts b/services/frontend/src/components/CustomPopulation/courseMatrix.ts
index 4f324e54a..cf09e243b 100644
--- a/services/frontend/src/components/CustomPopulation/courseMatrix.ts
+++ b/services/frontend/src/components/CustomPopulation/courseMatrix.ts
@@ -21,39 +21,39 @@ export type CourseMatrixAggregate = {
 
 /**
  * Passed completions of the student that are included in one of the student's study plans (HOPS).
- * Returns the latest completion per course id, sorted by course id.
+ * Returns the latest completion per course group, sorted by course group id.
  */
 export const getHopsCourses = (student: FormattedStudent): StudentCourse[] => {
   const hopsCourseIds = new Set(student.studyplans?.flatMap(plan => plan.included_courses ?? []) ?? [])
   const passedCoursesInHops = student.courses.filter(course => course.passed && hopsCourseIds.has(course.course_id))
 
-  const latestById = new Map<string, StudentCourse>()
+  const latestByGroupId = new Map<string, StudentCourse>()
   for (const course of passedCoursesInHops) {
-    if (!course.course_id) continue
+    if (!course.courseGroupId) continue
 
-    const existing = latestById.get(course.course_id)
+    const existing = latestByGroupId.get(course.courseGroupId)
     if (!existing || new Date(course.date).getTime() > new Date(existing.date).getTime()) {
-      latestById.set(course.course_id, course)
+      latestByGroupId.set(course.courseGroupId, course)
     }
   }
 
-  return [...latestById.values()].sort((a, b) => a.course_id.localeCompare(b.course_id))
+  return [...latestByGroupId.values()].sort((a, b) => a.courseGroupId.localeCompare(b.courseGroupId))
 }
 
 export const calculateExcelData = (
   students: FormattedStudent[],
-  courseInfoById: Map<string, { code: string; name: string }>
+  courseInfoByGroupId: Map<string, { code: string; name: string }>
 ) => {
-  // Keyed by course_id internally so different courses are never accidentally merged;
-  // code/name are only for display.
+  // Keyed by course groupId internally so different courses are never accidentally merged,
+  // while different versions of the same course are; code/name are only for display.
   const counters = new Map<string, { code: string; name: string; credits: number; students: Set<string> }>()
 
   const rows = students.map(student => {
     const courses = getHopsCourses(student).map(course => {
-      const id = course.course_id
-      const { code, name } = courseInfoById.get(id) ?? { code: id, name: '' }
-      const counter = counters.get(id) ?? { code, name, credits: 0, students: new Set() }
-      counters.set(id, counter)
+      const groupId = course.courseGroupId
+      const { code, name } = courseInfoByGroupId.get(groupId) ?? { code: course.course_code, name: '' }
+      const counter = counters.get(groupId) ?? { code, name, credits: 0, students: new Set() }
+      counters.set(groupId, counter)
       counter.credits += course.credits ?? 0
       counter.students.add(student.studentNumber)