diff --git a/test/util-test.cc b/test/util-test.cc
index a36feefe..b124e05a 100644
--- a/test/util-test.cc
+++ b/test/util-test.cc
@@ -815,7 +815,7 @@ TEST(UtilTest, FormatSystemError) {
   EXPECT_EQ(fmt::format("test: {}", get_system_error(EDOM)), message.str());
   message.clear();
   fmt::internal::format_system_error(
-        message, EDOM, fmt::StringRef("x", std::numeric_limits<size_t>::max()));
+        message, EDOM, fmt::StringRef(0, std::numeric_limits<size_t>::max()));
   EXPECT_EQ(fmt::format("error {}", EDOM), message.str());
 }
 
@@ -851,7 +851,7 @@ TEST(UtilTest, FormatWindowsError) {
   actual_message.clear();
   fmt::internal::format_windows_error(
         actual_message, ERROR_FILE_EXISTS,
-        fmt::StringRef("x", std::numeric_limits<size_t>::max()));
+        fmt::StringRef(0, std::numeric_limits<size_t>::max()));
   EXPECT_EQ(fmt::format("error {}", ERROR_FILE_EXISTS), actual_message.str());
 }