diff --git a/redfish-core/include/utils/extern/date.h b/redfish-core/include/utils/extern/date.h
index 209e267..ebeaeb1 100644
--- a/redfish-core/include/utils/extern/date.h
+++ b/redfish-core/include/utils/extern/date.h
@@ -980,8 +980,8 @@
 inline namespace literals
 {
 
-CONSTCD11 date::day  operator "" _d(unsigned long long d) NOEXCEPT;
-CONSTCD11 date::year operator "" _y(unsigned long long y) NOEXCEPT;
+CONSTCD11 date::day  operator ""_d(unsigned long long d) NOEXCEPT;
+CONSTCD11 date::year operator ""_y(unsigned long long y) NOEXCEPT;
 
 }  // inline namespace literals
 #endif // !defined(_MSC_VER) || (_MSC_VER >= 1900)
@@ -1989,7 +1989,7 @@
 CONSTCD11
 inline
 date::day
-operator "" _d(unsigned long long d) NOEXCEPT
+operator ""_d(unsigned long long d) NOEXCEPT
 {
     return date::day{static_cast<unsigned>(d)};
 }
@@ -1997,7 +1997,7 @@
 CONSTCD11
 inline
 date::year
-operator "" _y(unsigned long long y) NOEXCEPT
+operator ""_y(unsigned long long y) NOEXCEPT
 {
     return date::year(static_cast<int>(y));
 }