diff --git a/tools/services/font_service.py b/tools/services/font_service.py
index 73b772d..dd59b5a 100644
--- a/tools/services/font_service.py
+++ b/tools/services/font_service.py
@@ -11,7 +11,7 @@
 from tools.configs.font import FontConfig
 
 
-def collect_glyph_files(font_config: FontConfig) -> tuple[list[str], dict[int, str], list[GlyphFile]]:
+def collect_glyph_files(font_config: FontConfig) -> tuple[set[str], dict[int, str], list[GlyphFile]]:
     context = glyph_file_util.load_context(font_config.glyphs_dir)
 
     if font_config.fallback_lower_from_upper:
@@ -26,7 +26,7 @@ def collect_glyph_files(font_config: FontConfig) -> tuple[list[str], dict[int, s
             if code_point in context and fallback_code_point not in context:
                 context[fallback_code_point] = context[code_point]
 
-    alphabet = [chr(code_point) for code_point in context if code_point >= 0]
+    alphabet = {chr(code_point) for code_point in context if code_point >= 0}
     character_mapping = glyph_file_util.get_character_mapping(context)
     glyph_sequence = glyph_file_util.get_glyph_sequence(context)
     return alphabet, character_mapping, glyph_sequence
diff --git a/tools/services/template_service.py b/tools/services/template_service.py
index 9e10c23..7e9cef2 100644
--- a/tools/services/template_service.py
+++ b/tools/services/template_service.py
@@ -28,14 +28,14 @@ def _make_html(template_name: str, file_path: Path, params: dict[str, object] |
     logger.info("Make html: '{}'", file_path)
 
 
-def make_alphabet_html(font_config: FontConfig, alphabet: list[str]):
+def make_alphabet_html(font_config: FontConfig, alphabet: set[str]):
     _make_html('alphabet.html', font_config.outputs_dir.joinpath('alphabet.html'), {
         'font_config': font_config,
-        'alphabet': ''.join(alphabet),
+        'alphabet': ''.join(sorted(alphabet)),
     })
 
 
-def _handle_demo_html_element(alphabet: list[str], soup: bs4.BeautifulSoup, element: bs4.PageElement):
+def _handle_demo_html_element(alphabet: set[str], soup: bs4.BeautifulSoup, element: bs4.PageElement):
     if isinstance(element, bs4.element.Tag):
         for child_element in list(element.contents):
             _handle_demo_html_element(alphabet, soup, child_element)
@@ -75,7 +75,7 @@ def _handle_demo_html_element(alphabet: list[str], soup: bs4.BeautifulSoup, elem
         tmp_parent.unwrap()
 
 
-def make_demo_html(font_config: FontConfig, alphabet: list[str]):
+def make_demo_html(font_config: FontConfig, alphabet: set[str]):
     content_html = _environment.get_template('demo-content.html').render(font_config=font_config)
     content_html = ''.join(line.strip() for line in content_html.split('\n'))
     soup = bs4.BeautifulSoup(content_html, 'html.parser')