diff --git a/src/kernel-install/test-kernel-install.sh b/src/kernel-install/test-kernel-install.sh
index 7da8285969..e904ee5375 100755
--- a/src/kernel-install/test-kernel-install.sh
+++ b/src/kernel-install/test-kernel-install.sh
@@ -291,7 +291,7 @@ rmdir "$BOOT_ROOT/hoge"
 ###########################################
 output="$("$kernel_install" -v --json=pretty inspect 1.1.1 "$D/sources/linux")"
 
-diff -u <(echo "$output") - <<EOF
+diff -u <(echo "$output") - >&2 <<EOF
 {
 	"MachineID" : "3e0484f3634a418b8e6a39e8828b03e3",
 	"KernelImageType" : "unknown",
@@ -309,7 +309,7 @@ diff -u <(echo "$output") - <<EOF
 		"$D/00-skip.install"
 	],
 	"PluginEnvironment" : [
-		"LC_COLLATE=C.UTF-8",
+		"LC_COLLATE=$SYSTEMD_DEFAULT_LOCALE",
 		"KERNEL_INSTALL_VERBOSE=1",
 		"KERNEL_INSTALL_IMAGE_TYPE=unknown",
 		"KERNEL_INSTALL_MACHINE_ID=3e0484f3634a418b8e6a39e8828b03e3",
diff --git a/src/test/meson.build b/src/test/meson.build
index d5f133bca7..446336048a 100644
--- a/src/test/meson.build
+++ b/src/test/meson.build
@@ -14,6 +14,7 @@ path = run_command(sh, '-c', 'echo "$PATH"', check: true).stdout().strip()
 test_env = {
         'PATH' : meson.project_build_root() + ':' + path,
         'PROJECT_BUILD_ROOT' : meson.project_build_root(),
+        'SYSTEMD_DEFAULT_LOCALE' : get_option('default-locale'),
         'SYSTEMD_SLOW_TESTS' : want_slow_tests ? '1' : '0',
         'PYTHONDONTWRITEBYTECODE' : '1',
 }