diff --git a/build/build.py b/build/build.py
index f24384f..216cd15 100644
--- a/build/build.py
+++ b/build/build.py
@@ -15,20 +15,20 @@ def build(
         build_dir: Optional[Path] = None,
         input_file: Optional[Path] = None,
         author: Optional[str] = None,
-        latex_name: str = 'prepend-author',           # name handling
-        recursive: bool = False,                      # input control
-        include_timestamp: bool = False,              # header
-        include_pytex_version: bool = False,          # header
-        include_license: bool = False,                # header
-        include_git_version: bool = False,            # header
-        include_pytex_info_text: bool = False,        # header
+        latex_name: str = 'prepend-author',  # name handling
+        recursive: bool = False,  # input control
+        include_timestamp: bool = False,  # header
+        include_pytex_version: bool = False,  # header
+        include_license: bool = False,  # header
+        include_git_version: bool = False,  # header
+        include_pytex_info_text: bool = False,  # header
         extra_header: Optional[Path] = None,
-        allow_dirty: bool = False,                    # versioning
-        overwrite_existing_files: bool = False,       # output control
-        build_all: bool = False,                      # output control / versioning
-        write_build_information: bool = True,         # meta
+        allow_dirty: bool = False,  # versioning
+        overwrite_existing_files: bool = False,  # output control
+        build_all: bool = False,  # output control / versioning
+        write_build_information: bool = True,  # meta
         clean_old_files: bool = False
-        ):
+):
     pytex_msg('Getting git repository information...')
     if extra_header:
         if extra_header.exists():
@@ -95,8 +95,9 @@ def build(
     sources_to_build = []
     for file in files:
         if last_build_info:
-            last_build_info_for_this_file =\
-                list(filter(lambda i: i['source file'] == str(file.relative_to(src_dir)), last_build_info['tex_sources']))
+            last_build_info_for_this_file = \
+                list(filter(lambda i: i['source file'] == str(file.relative_to(src_dir)),
+                            last_build_info['tex_sources']))
         else:
             last_build_info_for_this_file = []
         sources_to_build.append(
@@ -147,8 +148,9 @@ def build(
                     file.unlink()
             elif not str(file.relative_to(output_dir)) in built_files:
                 if not file.is_dir() and not str(file.relative_to(output_dir)) == 'build_info.json':
-                    # PyTeX does not at all know something about this file
-                    raise UnknownFileInBuildDirectoryError(file.relative_to(output_dir))
+                    if '.git' not in str(file):
+                        # PyTeX does not at all know something about this file
+                        raise UnknownFileInBuildDirectoryError(file.relative_to(output_dir))
 
     if write_build_information:
         with open(output_dir / 'build_info.json', 'w') as f: