diff --git a/nix/modules/hive-ci.nix b/nix/modules/hive-ci.nix
index 6dc02848..4eeabf04 100644
--- a/nix/modules/hive-ci.nix
+++ b/nix/modules/hive-ci.nix
@@ -202,17 +202,11 @@ in
             "+${autoRegisterScript}"
           ];
 
-          # Tools available to workflow steps.
-          environment.systemPackages = [
-            pkgs.git
-            pkgs.nix
-            pkgs.cargo
-            pkgs.rustc
-            pkgs.rustfmt
-            pkgs.clippy
-            pkgs.curl
-            pkgs.jq
-          ];
+          # git is required by the runner's checkout step.
+          # Everything else (nix, rust tools) is either part of NixOS
+          # by default or pulled in hermetically by nix flake check.
+          # curl/jq in the autoregister preStart use absolute store paths.
+          environment.systemPackages = [ pkgs.git ];
         };
     };
   };