diff --git a/services/baremetal-builder/default.nix b/services/baremetal-builder/default.nix
index f3dfa70..b780d31 100644
--- a/services/baremetal-builder/default.nix
+++ b/services/baremetal-builder/default.nix
@@ -61,6 +61,11 @@ in
       device = "/dev/disk/by-label/hydra";
       fsType = "xfs";
     };
+    # We want the tmp filesystem on the same filesystem as the hydra store, so that builds can use reflinks
+    fileSystems."/tmp" = {
+      device = "/mnt/tmp";
+      options = [ "bind" ];
+    };
 
     fileSystems."/boot" = {
       device = "/dev/disk/by-label/BOOT";