diff --git a/src/exercises.py b/src/exercises.py
index 1d069d4..e509abf 100644
--- a/src/exercises.py
+++ b/src/exercises.py
@@ -9,8 +9,13 @@ class ExerciseWriteUp(FileHandle):
     def __init__(self, root_dir: Path, course):
         self.root_dir = root_dir
         self.course = course
-        FileHandle.__init__(self, next(self.root_dir.rglob('*.tex')), FileType.tex)
-
+        try:
+            tex_file = next(self.root_dir.rglob('*.tex'))
+        except StopIteration:
+            print("No valid '.tex' file found in directory {}, can't instantiate write up here".format(root_dir))
+            # TODO: raise proper error
+            exit(1)
+        FileHandle.__init__(self, tex_file, FileType.tex)
 
 class Exercise:
     def __init__(self, course, number: int):
@@ -52,7 +57,6 @@ class Exercises(list):
         self._solutions = None
         self._writeups = None
         self._sheets = Files(self.sheet_root)
-        self.ignored_folders = [self.sheet_root, self.solutions_root, self.root / 'LatexPackagesBuild', self.root / '.git']
         list.__init__(self, (Exercise(self.course, num) for num in map(lambda s: s.number, self._sheets)))
 
     @property
@@ -68,7 +72,7 @@ class Exercises(list):
     @property
     def writeups(self):
         if not self._writeups:
-            dirs = list(d for d in self.root.iterdir() if d.is_dir() and d not in self.ignored_folders)
+            dirs = [d for d in self.root.glob('ub*') if d.is_dir()]
             self._writeups = sorted((ExerciseWriteUp(d, self.course) for d in dirs), key=lambda e: e.number)
         return self._writeups