diff --git a/mkdocs_exporter/plugin.py b/mkdocs_exporter/plugin.py
index 4f24931..0595704 100644
--- a/mkdocs_exporter/plugin.py
+++ b/mkdocs_exporter/plugin.py
@@ -64,7 +64,7 @@ def on_post_build(self, **kwargs) -> None:
     for file in self.files:
       css = None
 
-      with open(file.abs_dest_path, 'r') as reader:
+      with open(file.abs_dest_path, 'r', encoding='utf-8') as reader:
         css = self.theme.stylesheet(reader.read())
-      with open(file.abs_dest_path, 'w+') as writer:
+      with open(file.abs_dest_path, 'w+', encoding='utf-8') as writer:
         writer.write(css)
diff --git a/mkdocs_exporter/plugins/pdf/plugin.py b/mkdocs_exporter/plugins/pdf/plugin.py
index e4a4fb0..24e3a00 100644
--- a/mkdocs_exporter/plugins/pdf/plugin.py
+++ b/mkdocs_exporter/plugins/pdf/plugin.py
@@ -53,10 +53,10 @@ def on_page_markdown(self, markdown: str, page: Page, config: Config, **kwargs)
     covers = {**self.config.covers, **{k: os.path.join(os.path.dirname(config['config_file_path']), v) for k, v in page.meta.get('covers', {}).items()}}
 
     if covers.get('front'):
-      with open(covers['front'], 'r') as file:
+      with open(covers['front'], 'r', encoding='utf-8') as file:
         content = self.renderer.cover(file.read()) + content
     if covers.get('back'):
-      with open(covers['back'], 'r') as file:
+      with open(covers['back'], 'r', encoding='utf-8') as file:
         content = content + self.renderer.cover(file.read())
 
     for path in [path for path in covers.values() if path is not None]:
diff --git a/mkdocs_exporter/plugins/pdf/renderer.py b/mkdocs_exporter/plugins/pdf/renderer.py
index 80e8b0b..4c4c535 100644
--- a/mkdocs_exporter/plugins/pdf/renderer.py
+++ b/mkdocs_exporter/plugins/pdf/renderer.py
@@ -62,10 +62,10 @@ async def render(self, page: Page) -> bytes:
     page.theme.preprocess(preprocessor)
 
     for stylesheet in self.stylesheets:
-      with open(stylesheet, 'r') as file:
+      with open(stylesheet, 'r', encoding='utf-8') as file:
         preprocessor.stylesheet(file.read())
     for script in self.scripts:
-      with open(script, 'r') as file:
+      with open(script, 'r', encoding='utf-8') as file:
         preprocessor.script(file.read())
 
     preprocessor.script(importlib_resources.files(js).joinpath('pagedjs.min.js').read_text())