diff --git a/argparse.vp b/argparse.vp
index 6d5c6dd..51c2225 100644
--- a/argparse.vp
+++ b/argparse.vp
@@ -201,7 +201,7 @@ class ArgumentParser:
         """Match prefix for --name=value syntax"""
         for i in range(self._arg_count):
             arg: Argument* = self._get_arg(i)
-            name_len: int = string.strlen(arg.name)
+            name_len: int = int(string.strlen(arg.name))    # 显式 cast：避免 64→32 隐式窄化
             if string.strncmp(token, arg.name, name_len) == 0:
                 if token[name_len] == '=':
                     return i
@@ -329,7 +329,7 @@ class ArgumentParser:
                         release(args)
                         return None
                     arg = self._get_arg(found)
-                    arg_name_len: int = string.strlen(arg.name)
+                    arg_name_len: int = int(string.strlen(arg.name))    # 显式 cast：避免 64→32 隐式窄化
                     value = token + arg_name_len + 1
                     self._store_value(args, arg, value)
                     idx += 1
diff --git a/ast/parser.vp b/ast/parser.vp
index 8b36a03..e5c8bba 100644
--- a/ast/parser.vp
+++ b/ast/parser.vp
@@ -3199,8 +3199,8 @@ def _parse_from_import(ps: Parser*) -> AST*:
             _advance(ps)
             if _cur_type(ps) == TokenType.Name and _cur_kw(ps) == Keyword.NotKeyword:
                 next_name: str = _cur_str(ps)
-                mlen: int = string.strlen(module_name)
-                nlen: int = string.strlen(next_name)
+                mlen: int = int(string.strlen(module_name))    # 显式 cast：避免 64→32 隐式窄化
+                nlen: int = int(string.strlen(next_name))    # 显式 cast：避免 64→32 隐式窄化
                 new_mod: str = ps.pool.alloc(mlen + 1 + nlen + 1)
                 if new_mod is not None:
                     string.strcpy(new_mod, module_name)
@@ -3252,8 +3252,8 @@ def _parse_alias_list(ps: Parser*) -> list[AST*]*:
             _advance(ps)
             if _cur_type(ps) == TokenType.Name:
                 next_n: str = _cur_str(ps)
-                nmlen: int = string.strlen(name_str)
-                nxtlen: int = string.strlen(next_n)
+                nmlen: int = int(string.strlen(name_str))    # 显式 cast：避免 64→32 隐式窄化
+                nxtlen: int = int(string.strlen(next_n))    # 显式 cast：避免 64→32 隐式窄化
                 new_name: str = ps.pool.alloc(nmlen + 1 + nxtlen + 1)
                 if new_name is not None:
                     string.strcpy(new_name, name_str)
diff --git a/gzip.vp b/gzip.vp
index 2c81dd1..11867d1 100644
--- a/gzip.vp
+++ b/gzip.vp
@@ -59,7 +59,7 @@ class GzipFile:
             f.close()
             self.err = -4
             return
-        got: LONG = f.read_all(buf, ULONG(self.src_len + 1))
+        got: LONG = f.read_all(buf, self.src_len + 1)    # 去掉 ULONG 显式窄化：read_all 的 buf_size 形参本就是 sizet，直接以 sizet 传更安全
         f.close()
         if got <= 0 or sizet(got) != self.src_len:
             stdlib.free(buf)