diff --git a/pkgs/top-level/python-packages.nix b/pkgs/top-level/python-packages.nix
index 39bf7676d67..db6043fdfc0 100644
--- a/pkgs/top-level/python-packages.nix
+++ b/pkgs/top-level/python-packages.nix
@@ -4944,6 +4944,8 @@ in modules // {
       sha256 = "0fwydaahgflz9w753v1cmkfzrlfq1vb8zp4i20m2d3lvkm4crv93";
     };
 
+    buildInputs = with self; [ pytest ];
+
     meta = with stdenv.lib; {
       description = "Scripting library for tmux";
       homepage = https://libtmux.readthedocs.io/;