diff --git a/shell.nix b/shell.nix
index 7a073d6..3de8d37 100644
--- a/shell.nix
+++ b/shell.nix
@@ -12,6 +12,6 @@ in
       libffi
       libxml2
       clippy
-      python3.withPackages(ps: [ps.numpy])
+      (python3.withPackages(ps: [ps.numpy]))
     ];
   }