diff --git a/requirements.txt b/requirements.txt
index 357269b4..3c043066 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -20,6 +20,7 @@ Pygments~=2.17.2
 pytz~=2024.1
 PyYAML~=6.0.1
 pillow~=10.0.0
+pdm-backend~=2.3.3
 starlette~=0.36.3
 toml~=0.10.2
 loguru~=0.7.2