diff --git a/redfish-core/ut/time_utils_test.cpp b/redfish-core/ut/time_utils_test.cpp
index 86174ba..d03c316 100644
--- a/redfish-core/ut/time_utils_test.cpp
+++ b/redfish-core/ut/time_utils_test.cpp
@@ -24,7 +24,7 @@
     EXPECT_EQ(fromDurationString("P1T"), std::nullopt);
     EXPECT_EQ(fromDurationString("PT100M1000S100"), std::nullopt);
     EXPECT_EQ(fromDurationString("PDTHMS"), std::nullopt);
-    EXPECT_EQ(fromDurationString("P99999999999999999DT"), std::nullopt);
+    EXPECT_EQ(fromDurationString("P9999999999999999999999999DT"), std::nullopt);
     EXPECT_EQ(fromDurationString("PD222T222H222M222.222S"), std::nullopt);
     EXPECT_EQ(fromDurationString("PT99999H9999999999999999999999M99999999999S"),
               std::nullopt);