diff --git a/base.py b/base.py
index 1013ee2..e2cabbb 100644
--- a/base.py
+++ b/base.py
@@ -78,9 +78,15 @@ def file_size(p: Path) -> str:
 
 gr_values: Set[str] = set(PINYIN_TO["romatzyh"].values())  # 国语罗马字的有效拼写
 cy_values: Set[str] = set(PINYIN_TO["cyrillic"].values())  # 西里尔转写的有效拼写
-tone_to_ipa: Ldata = {"1": "˥", "2": "˧˥", "3": "˨˩˦", "4": "˥˩", "5": ""}  # IPA声调
+TONE_TO_IPA: Final[Ldata] = {
+    "1": "˥",
+    "2": "˧˥",
+    "3": "˨˩˦",
+    "4": "˥˩",
+    "5": "",
+}  # IPA声调
 
 rep_zh: Ldata = load_json("rep_zh")  # 连写的中文转写方案替换修正
-finals: Tuple[str, ...] = tuple("aāááàoōóǒòeēéěè")  # 可能的零声母开头
+PINYIN_FINALS: Final[Tuple[str, ...]] = tuple("aāááàoōóǒòeēéěè")  # 可能的零声母开头
 
 rep_ja_kk: Ldata = load_json("rep_ja_kk")  # 片假名替换修正
diff --git a/converter.py b/converter.py
index 176d8f1..ccfa11e 100644
--- a/converter.py
+++ b/converter.py
@@ -19,8 +19,8 @@
     PINYIN_TO,
     gr_values,
     cy_values,
-    tone_to_ipa,
-    finals,
+    TONE_TO_IPA,
+    PINYIN_FINALS,
     rep_zh,
     rep_ja_kk,
 )
@@ -348,7 +348,7 @@ def to_pinyin(self, text: str) -> str:
                 (
                     f"'{py}"
                     if i > 0
-                    and py.startswith(finals)
+                    and py.startswith(PINYIN_FINALS)
                     and pinyin_list[i - 1][-1].isalpha()
                     else py
                 )
@@ -414,7 +414,7 @@ def to_ipa(self, text: str) -> str:
         """
         pinyin_list = lazy_pinyin(text, style=Style.TONE3, neutral_tone_with_five=True)
         ipa_list = [
-            f"{PINYIN_TO['ipa'].get(p[:-1], p[:-1])}{tone_to_ipa.get(p[-1], p[-1])}"
+            f"{PINYIN_TO['ipa'].get(p[:-1], p[:-1])}{TONE_TO_IPA.get(p[-1], p[-1])}"
             for p in pinyin_list
         ]
         return " ".join(ipa_list)