diff --git a/tests/functional/bash-profile.sh b/tests/functional/bash-profile.sh
index 3faeaaba1..01e869202 100644
--- a/tests/functional/bash-profile.sh
+++ b/tests/functional/bash-profile.sh
@@ -2,7 +2,7 @@ source common.sh
 
 sed -e "s|@localstatedir@|$TEST_ROOT/profile-var|g" -e "s|@coreutils@|$coreutils|g" < ../../scripts/nix-profile.sh.in > $TEST_ROOT/nix-profile.sh
 
-user=$(whoami)
+user=$(whoami || echo -n nixbld)
 rm -rf $TEST_HOME $TEST_ROOT/profile-var
 mkdir -p $TEST_HOME
 USER=$user $SHELL -e -c ". $TEST_ROOT/nix-profile.sh; set"
diff --git a/tests/functional/init.sh b/tests/functional/init.sh
index f5a04f62e..663d04721 100755
--- a/tests/functional/init.sh
+++ b/tests/functional/init.sh
@@ -28,7 +28,7 @@ substituters =
 flake-registry = $TEST_ROOT/registry.json
 show-trace = true
 include nix.conf.extra
-trusted-users = $(whoami)
+trusted-users = $(whoami || id -u)
 EOF
 
 cat > "$NIX_CONF_DIR"/nix.conf.extra <<EOF