diff --git a/modules/installer/tools/nixos-rebuild.sh b/modules/installer/tools/nixos-rebuild.sh
index 7fd0908a935..9bb13061ed9 100644
--- a/modules/installer/tools/nixos-rebuild.sh
+++ b/modules/installer/tools/nixos-rebuild.sh
@@ -49,6 +49,7 @@ action=
 buildNix=1
 rollback=
 upgrade=
+repair=
 
 while [ "$#" -gt 0 ]; do
     i="$1"; shift 1
@@ -71,6 +72,10 @@ while [ "$#" -gt 0 ]; do
       --upgrade)
         upgrade=1
         ;;
+      --repair)
+        repair=1
+        extraBuildFlags+=("$i")
+        ;;
       --show-trace|--no-build-hook|--keep-failed|-K|--keep-going|-k|--verbose|-v|--fallback|--repair)
         extraBuildFlags+=("$i")
         ;;
@@ -111,7 +116,9 @@ trap 'rm -rf "$tmpDir"' EXIT
 # This matters if the new Nix in Nixpkgs has a schema change.  It
 # would upgrade the schema, which should only happen once we actually
 # switch to the new configuration.
-if systemctl show nix-daemon.socket nix-daemon.service | grep -q ActiveState=active; then
+# If --repair is given, don't try to use the Nix daemon, because the
+# flag can only be used directly.
+if [ -z "$repair" ] && systemctl show nix-daemon.socket nix-daemon.service | grep -q ActiveState=active; then
     export NIX_REMOTE=${NIX_REMOTE:-daemon}
 fi