diff --git a/tests/init.sh b/tests/init.sh
index 37480f52bd..5be999e4b1 100644
--- a/tests/init.sh
+++ b/tests/init.sh
@@ -17,6 +17,7 @@ mkdir "$NIX_DB_DIR"
 mkdir "$NIX_CONF_DIR"
 
 cat > "$NIX_CONF_DIR"/nix.conf <<EOF
+build-users-group =
 gc-keep-outputs = false
 gc-keep-derivations = false
 env-keep-derivations = false