diff --git a/lms/extractors/imagefile.py b/lms/extractors/imagefile.py
index 0fe38096..f7a15e73 100644
--- a/lms/extractors/imagefile.py
+++ b/lms/extractors/imagefile.py
@@ -15,7 +15,7 @@ def __init__(self, **kwargs):
         )
 
     def can_extract(self) -> bool:
-        return self.ext in ALLOWED_IMAGES_EXTENSIONS
+        return self.ext.lower() in ALLOWED_IMAGES_EXTENSIONS
 
     def get_exercise(self, to_extract: bytes) -> Tuple[int, List[File]]:
         exercise_id = 0
@@ -25,7 +25,7 @@ def get_exercise(self, to_extract: bytes) -> Tuple[int, List[File]]:
             raise BadUploadFile("Can't resolve exercise id.", self.filename)
 
         decoded = base64.b64encode(to_extract)
-        return (exercise_id, [File(f'/main.{self.ext}', decoded)])
+        return (exercise_id, [File(f'/main.{self.ext.lower()}', decoded)])
 
     def get_exercises(self) -> Iterator[Tuple[int, List[File]]]:
         exercise_id, files = self.get_exercise(self.file_content)
diff --git a/lms/extractors/textfile.py b/lms/extractors/textfile.py
index 5a2b1e23..227965e6 100644
--- a/lms/extractors/textfile.py
+++ b/lms/extractors/textfile.py
@@ -20,7 +20,7 @@ def __init__(self, **kwargs):
         )
 
     def can_extract(self) -> bool:
-        if self.ext not in ALLOWED_EXTENSIONS:
+        if self.ext.lower() not in ALLOWED_EXTENSIONS:
             return False
         if isinstance(self.file_content, str):
             return True
@@ -34,7 +34,7 @@ def get_exercise(self, to_extract: str) -> Tuple[int, List[File]]:
         if not exercise_id:
             raise BadUploadFile("Can't resolve exercise id.", self.filename)
 
-        return (exercise_id, [File(f'/main.{self.ext}', content)])
+        return (exercise_id, [File(f'/main.{self.ext.lower()}', content)])
 
     def get_exercises(self) -> Iterator[Tuple[int, List[File]]]:
         exercise_id, files = self.get_exercise(self.file_content)
diff --git a/lms/extractors/ziparchive.py b/lms/extractors/ziparchive.py
index 89507d3a..de1ff1ac 100644
--- a/lms/extractors/ziparchive.py
+++ b/lms/extractors/ziparchive.py
@@ -43,14 +43,14 @@ def _extract(archive: ZipFile, filename: str, dirname: str = '') -> File:
         with archive.open(filename) as current_file:
             log.debug(f'Extracting from archive: {filename}')
             code = current_file.read()
-        if filename.rpartition('.')[-1] in ALLOWED_IMAGES_EXTENSIONS:
+        if filename.rpartition('.')[-1].lower() in ALLOWED_IMAGES_EXTENSIONS:
             decoded = base64.b64encode(code)
         else:
             decoded = code.decode(
                 'utf-8', errors='replace',
             ).replace('\x00', '')
         filename = filename[len(dirname):]
-        return File(path=f'/{filename}', code=decoded)
+        return File(path=f'/{filename.lower()}', code=decoded)
 
     def get_files(
         self, archive: ZipFile, filenames: List[Text], dirname: str = '',