diff --git a/fiasko_bro/pre_validation_checks/files_len.py b/fiasko_bro/pre_validation_checks/files_len.py
new file mode 100644
index 0000000..221c665
--- /dev/null
+++ b/fiasko_bro/pre_validation_checks/files_len.py
@@ -0,0 +1,12 @@
+from ..utils import url_helpers
+
+
+def has_no_long_files(solution_repo, max_number_of_lines, *args, **kwargs):
+    for file_path, file_content, _ in solution_repo.get_ast_trees(
+        with_filenames=True,
+        with_file_content=True
+    ):
+        number_of_lines = file_content.count('\n')
+        if number_of_lines > max_number_of_lines:
+            file_name = url_helpers.get_filename_from_path(file_path)
+            return 'file_too_long', file_name