diff --git a/avatar/conf.py b/avatar/conf.py
index 4a84407..1a66e21 100644
--- a/avatar/conf.py
+++ b/avatar/conf.py
@@ -22,6 +22,7 @@ class AvatarConf(AppConf):
     HASH_USERDIRNAMES = False
     EXPOSE_USERNAMES = False
     ALLOWED_FILE_EXTS = None
+    ALLOWED_MIMETYPES = None
     CACHE_TIMEOUT = 60 * 60
     STORAGE = settings.DEFAULT_FILE_STORAGE
     CLEANUP_DELETED = True
diff --git a/avatar/forms.py b/avatar/forms.py
index 0cceb42..745bae3 100644
--- a/avatar/forms.py
+++ b/avatar/forms.py
@@ -29,6 +29,34 @@ class UploadAvatarForm(forms.Form):
     def clean_avatar(self):
         data = self.cleaned_data["avatar"]
 
+        if settings.AVATAR_ALLOWED_MIMETYPES:
+            try:
+                import magic
+            except ImportError:
+                raise ImportError(
+                    "python-magic library must be installed in order to use uploaded file content limitation"
+                )
+
+            # Construct 256 bytes needed for mime validation
+            magic_buffer = bytes()
+            for chunk in data.chunks():
+                magic_buffer += chunk
+                if len(magic_buffer) >= 256:
+                    break
+
+            # https://github.com/ahupp/python-magic#usage
+            mime = magic.from_buffer(magic_buffer, mime=True)
+            if mime not in settings.AVATAR_ALLOWED_MIMETYPES:
+                raise forms.ValidationError(
+                    _(
+                        "File content is invalid. Detected: %(mimetype)s Allowed content types are: %(valid_mime_list)s"
+                    )
+                    % {
+                        "valid_mime_list": ", ".join(settings.AVATAR_ALLOWED_MIMETYPES),
+                        "mimetype": mime,
+                    }
+                )
+
         if settings.AVATAR_ALLOWED_FILE_EXTS:
             root, ext = os.path.splitext(data.name.lower())
             if ext not in settings.AVATAR_ALLOWED_FILE_EXTS:
diff --git a/tests/data/test.tiff b/tests/data/test.tiff
new file mode 100644
index 0000000..c3d899b
Binary files /dev/null and b/tests/data/test.tiff differ
diff --git a/tests/requirements.txt b/tests/requirements.txt
index cee13f4..04d12f0 100644
--- a/tests/requirements.txt
+++ b/tests/requirements.txt
@@ -1,2 +1,3 @@
 coverage==6.2
 django
+python-magic
diff --git a/tests/tests.py b/tests/tests.py
index cce39ac..3045a08 100644
--- a/tests/tests.py
+++ b/tests/tests.py
@@ -117,15 +117,27 @@ class AvatarTests(TestCase):
         self.assertEqual(avatar.user, self.user)
         self.assertTrue(avatar.primary)
 
+    # We allow the .tiff file extension but not the mime type
+    @override_settings(AVATAR_ALLOWED_FILE_EXTS=(".png", ".gif", ".jpg", ".tiff"))
+    @override_settings(
+        AVATAR_ALLOWED_MIMETYPES=("image/png", "image/gif", "image/jpeg")
+    )
+    def test_unsupported_image_format_upload(self):
+        """Check with python-magic that we detect corrupted / unapprovd image files correctly"""
+        response = upload_helper(self, "test.tiff")
+        self.assertEqual(response.status_code, 200)
+        self.assertEqual(len(response.redirect_chain), 0)  # Redirect only if it worked
+        self.assertNotEqual(response.context["upload_avatar_form"].errors, {})
+
+    @override_settings(AVATAR_ALLOWED_FILE_EXTS=(".jpg", ".png"))
     def test_image_without_wrong_extension(self):
-        # use with AVATAR_ALLOWED_FILE_EXTS = ('.jpg', '.png')
         response = upload_helper(self, "imagefilewithoutext")
         self.assertEqual(response.status_code, 200)
         self.assertEqual(len(response.redirect_chain), 0)  # Redirect only if it worked
         self.assertNotEqual(response.context["upload_avatar_form"].errors, {})
 
+    @override_settings(AVATAR_ALLOWED_FILE_EXTS=(".jpg", ".png"))
     def test_image_with_wrong_extension(self):
-        # use with AVATAR_ALLOWED_FILE_EXTS = ('.jpg', '.png')
         response = upload_helper(self, "imagefilewithwrongext.ogg")
         self.assertEqual(response.status_code, 200)
         self.assertEqual(len(response.redirect_chain), 0)  # Redirect only if it worked