diff --git a/pkgs/development/python-modules/semaphore-bot/default.nix b/pkgs/development/python-modules/semaphore-bot/default.nix
index e69a920bc8ea..a0989fda28dc 100644
--- a/pkgs/development/python-modules/semaphore-bot/default.nix
+++ b/pkgs/development/python-modules/semaphore-bot/default.nix
@@ -21,7 +21,7 @@ buildPythonPackage rec {
   pythonRelaxDeps = [
     "anyio"
     "attrs"
-    "python-dateutil"
+    "python_dateutil"
   ];
 
   build-system = [ setuptools ];