diff --git a/requirements.txt b/requirements.txt
index 0570772..3daa2bc 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,6 +1,8 @@
 PyQt5>=5.15.2
 pywin32>=312; sys_platform == "win32"
-chardet>=4.0.0
+# chardet 6+ requires Python >=3.10.
+chardet>=5.2.0,<6; python_version < "3.10"
+chardet>=7.6.0; python_version >= "3.10"
 # psutil 是 fastpip 的依赖。fastpip 已 vendored 到 src/fastpip/（见下方说明），
 # 不再作为 PyPI 依赖自动带入，因此这里显式声明。
 psutil>=7.2.2