diff --git a/hosts/yarn/default.nix b/hosts/yarn/default.nix
index 777b4d4..65217fe 100644
--- a/hosts/yarn/default.nix
+++ b/hosts/yarn/default.nix
@@ -98,15 +98,26 @@
             pkgs.nix
           ]
         }
+
         STORE_PATH=$(curl -sf --max-time 30 "https://nix-cache.sigkill.computer/deploy/yarn" || true)
         if [ -z "$STORE_PATH" ]; then
           echo "server unreachable"
           exit 1
         fi
-        echo "applying $STORE_PATH"
-        nix-store -r "$STORE_PATH" || { echo "fetch failed"; exit 1; }
-        nix-env -p /nix/var/nix/profiles/system --set "$STORE_PATH" || { echo "profile set failed"; exit 1; }
-        "$STORE_PATH/bin/switch-to-configuration" boot || { echo "boot entry failed"; exit 1; }
+
+        CURRENT=$(readlink -f /nix/var/nix/profiles/system)
+        if [ "$CURRENT" = "$STORE_PATH" ]; then
+          echo "already up to date: $STORE_PATH"
+          exit 0
+        fi
+
+        echo "applying $STORE_PATH (was $CURRENT)"
+        nix-store -r --add-root /nix/var/nix/gcroots/pull-update-apply-latest --indirect "$STORE_PATH" \
+          || { echo "fetch failed"; exit 1; }
+        nix-env -p /nix/var/nix/profiles/system --set "$STORE_PATH" \
+          || { echo "profile set failed"; exit 1; }
+        "$STORE_PATH/bin/switch-to-configuration" boot \
+          || { echo "boot entry failed"; exit 1; }
         echo "update applied; reboot required"
       '';
     };