diff --git a/app/Filament/Pages/Learning/StudyGroup/Index.php b/app/Filament/Pages/Learning/StudyGroup/Index.php
index 325e628..da34c3c 100644
--- a/app/Filament/Pages/Learning/StudyGroup/Index.php
+++ b/app/Filament/Pages/Learning/StudyGroup/Index.php
@@ -162,7 +162,7 @@ public function studyGroupFormSchema(): array
                         ->options(function (Get $get, ?StudyGroup $record) {
                             $query = Student::query();
 
-                            $courseIds = array_values(array_filter((array) ($get('courses') ?? [])));
+                            $courseIds = array_values(array_filter((array) ($get('course_id') ?? [])));
                             if (! empty($courseIds)) {
                                 $allBusyIds = StudyGroup::getBusyStudentIdsForCourses(
                                     courseIds: $courseIds,
@@ -186,7 +186,7 @@ public function studyGroupFormSchema(): array
                             titleAttribute: 'full_name',
                             modifyQueryUsing: function (Builder $query, Get $get, ?StudyGroup $record) {
 
-                                $courseIds = array_values(array_filter((array) ($get('courses') ?? [])));
+                                $courseIds = array_values(array_filter((array) ($get('course_id') ?? [])));
                                 if (! empty($courseIds)) {
                                     $allBusyIds = StudyGroup::getBusyStudentIdsForCourses(
                                         courseIds: $courseIds,
diff --git a/app/Models/Course.php b/app/Models/Course.php
index e80adc3..96e6a2d 100644
--- a/app/Models/Course.php
+++ b/app/Models/Course.php
@@ -6,6 +6,7 @@
 use Illuminate\Database\Eloquent\Factories\HasFactory;
 use Illuminate\Database\Eloquent\Model;
 use Illuminate\Database\Eloquent\Relations\BelongsTo;
+use Illuminate\Database\Eloquent\Relations\BelongsToMany;
 use Illuminate\Database\Eloquent\Relations\HasMany;
 use Illuminate\Database\Eloquent\SoftDeletes;
 
@@ -32,7 +33,7 @@ public function materials(): HasMany
         return $this->hasMany(Material::class);
     }
 
-    public function studyGroups(): \Illuminate\Database\Eloquent\Relations\BelongsToMany
+    public function studyGroups(): BelongsToMany
     {
         return $this->belongsToMany(StudyGroup::class, 'study_group_courses');
     }