diff --git a/http/ut/utility_test.cpp b/http/ut/utility_test.cpp
index 191a16a..fc8b90e 100644
--- a/http/ut/utility_test.cpp
+++ b/http/ut/utility_test.cpp
@@ -56,3 +56,22 @@
     EXPECT_TRUE(crow::utility::base64Decode(encoded, decoded));
     EXPECT_EQ(data, decoded);
 }
+
+TEST(Utility, GetDateTime)
+{
+    // some time before the epoch
+    EXPECT_EQ(crow::utility::getDateTimeStdtime(std::time_t{-1234567}),
+              "1969-12-17T17:03:53Z");
+    // epoch
+    EXPECT_EQ(crow::utility::getDateTimeStdtime(std::time_t{0}),
+              "1970-01-01T00:00:00Z");
+    // some time in the past after the epoch
+    EXPECT_EQ(crow::utility::getDateTimeUint(uint64_t{1638312095}),
+              "2021-11-30T22:41:35Z");
+    // some time in the future, beyond 2038
+    EXPECT_EQ(crow::utility::getDateTimeUint(uint64_t{41638312095}),
+              "3289-06-18T21:48:15Z");
+    // the maximum time we support
+    EXPECT_EQ(crow::utility::getDateTimeUint(uint64_t{253402300799}),
+              "9999-12-31T23:59:59Z");
+}
diff --git a/http/utility.hpp b/http/utility.hpp
index 6f81be8..d141056 100644
--- a/http/utility.hpp
+++ b/http/utility.hpp
@@ -1,9 +1,10 @@
 #pragma once
-
 #include "nlohmann/json.hpp"
 
 #include <openssl/crypto.h>
 
+#include <boost/date_time/posix_time/posix_time.hpp>
+
 #include <chrono>
 #include <cstdint>
 #include <cstring>
@@ -572,26 +573,28 @@
 }
 
 /**
- * Method returns Date Time information according to requested format
+ * Method returns Date Time information in the ISO extended format
  *
- * @param[in] time time in second since the Epoch
+ * @param[in] timestamp in second since the Epoch; it can be negative
  *
- * @return Date Time according to requested format
+ * @return Date Time in the ISO extended format
  */
-inline std::string getDateTime(const std::time_t& time)
+inline std::string getDateTime(boost::posix_time::seconds secondsSinceEpoch)
 {
-    std::array<char, 128> dateTime;
-    std::string redfishDateTime("0000-00-00T00:00:00Z00:00");
+    boost::posix_time::ptime epoch(boost::gregorian::date(1970, 1, 1));
+    boost::posix_time::ptime time = epoch + secondsSinceEpoch;
+    // append zero offset to the end according to the Redfish spec for Date-Time
+    return boost::posix_time::to_iso_extended_string(time) + 'Z';
+}
 
-    if (std::strftime(dateTime.begin(), dateTime.size(), "%FT%T%z",
-                      std::localtime(&time)))
-    {
-        // insert the colon required by the ISO 8601 standard
-        redfishDateTime = std::string(dateTime.data());
-        redfishDateTime.insert(redfishDateTime.end() - 2, ':');
-    }
+inline std::string getDateTimeUint(uint64_t secondsSinceEpoch)
+{
+    return getDateTime(boost::posix_time::seconds(secondsSinceEpoch));
+}
 
-    return redfishDateTime;
+inline std::string getDateTimeStdtime(std::time_t secondsSinceEpoch)
+{
+    return getDateTime(boost::posix_time::seconds(secondsSinceEpoch));
 }
 
 /**
@@ -606,7 +609,7 @@
 inline std::pair<std::string, std::string> getDateTimeOffsetNow()
 {
     std::time_t time = std::time(nullptr);
-    std::string dateTime = getDateTime(time);
+    std::string dateTime = getDateTimeStdtime(time);
 
     /* extract the local Time Offset value from the
      * recevied dateTime string.
diff --git a/redfish-core/lib/certificate_service.hpp b/redfish-core/lib/certificate_service.hpp
index 045426e..8a78317 100644
--- a/redfish-core/lib/certificate_service.hpp
+++ b/redfish-core/lib/certificate_service.hpp
@@ -643,9 +643,8 @@
                         std::get_if<uint64_t>(&property.second);
                     if (value)
                     {
-                        std::time_t time = static_cast<std::time_t>(*value);
                         asyncResp->res.jsonValue["ValidNotAfter"] =
-                            crow::utility::getDateTime(time);
+                            crow::utility::getDateTimeUint(*value);
                     }
                 }
                 else if (property.first == "ValidNotBefore")
@@ -654,9 +653,8 @@
                         std::get_if<uint64_t>(&property.second);
                     if (value)
                     {
-                        std::time_t time = static_cast<std::time_t>(*value);
                         asyncResp->res.jsonValue["ValidNotBefore"] =
-                            crow::utility::getDateTime(time);
+                            crow::utility::getDateTimeUint(*value);
                     }
                 }
             }
diff --git a/redfish-core/lib/log_services.hpp b/redfish-core/lib/log_services.hpp
index fb515fe..074c927 100644
--- a/redfish-core/lib/log_services.hpp
+++ b/redfish-core/lib/log_services.hpp
@@ -180,8 +180,7 @@
                          << strerror(-ret);
         return false;
     }
-    entryTimestamp = crow::utility::getDateTime(
-        static_cast<std::time_t>(timestamp / 1000 / 1000));
+    entryTimestamp = crow::utility::getDateTimeUint(timestamp / 1000 / 1000);
     return true;
 }
 
@@ -419,7 +418,7 @@
                 {
                     continue;
                 }
-                std::time_t timestamp;
+                uint64_t timestamp = 0;
                 uint64_t size = 0;
                 std::string dumpStatus;
                 nlohmann::json thisEntry;
@@ -485,8 +484,7 @@
                                     messages::internalError(asyncResp->res);
                                     break;
                                 }
-                                timestamp =
-                                    static_cast<std::time_t>(*usecsTimeStamp);
+                                timestamp = (*usecsTimeStamp / 1000 / 1000);
                                 break;
                             }
                         }
@@ -505,7 +503,8 @@
                 thisEntry["@odata.id"] = dumpPath + entryID;
                 thisEntry["Id"] = entryID;
                 thisEntry["EntryType"] = "Event";
-                thisEntry["Created"] = crow::utility::getDateTime(timestamp);
+                thisEntry["Created"] =
+                    crow::utility::getDateTimeUint(timestamp);
                 thisEntry["Name"] = dumpType + " Dump Entry";
 
                 thisEntry["AdditionalDataSizeBytes"] = size;
@@ -578,7 +577,7 @@
                 }
 
                 foundDumpEntry = true;
-                std::time_t timestamp;
+                uint64_t timestamp = 0;
                 uint64_t size = 0;
                 std::string dumpStatus;
 
@@ -635,8 +634,7 @@
                                     messages::internalError(asyncResp->res);
                                     break;
                                 }
-                                timestamp =
-                                    static_cast<std::time_t>(*usecsTimeStamp);
+                                timestamp = *usecsTimeStamp / 1000 / 1000;
                                 break;
                             }
                         }
@@ -660,7 +658,7 @@
                 asyncResp->res.jsonValue["Id"] = entryID;
                 asyncResp->res.jsonValue["EntryType"] = "Event";
                 asyncResp->res.jsonValue["Created"] =
-                    crow::utility::getDateTime(timestamp);
+                    crow::utility::getDateTimeUint(timestamp);
                 asyncResp->res.jsonValue["Name"] = dumpType + " Dump Entry";
 
                 asyncResp->res.jsonValue["AdditionalDataSizeBytes"] = size;
@@ -1490,9 +1488,9 @@
                         thisEntry["Severity"] =
                             translateSeverityDbusToRedfish(*severity);
                         thisEntry["Created"] =
-                            crow::utility::getDateTime(timestamp);
+                            crow::utility::getDateTimeStdtime(timestamp);
                         thisEntry["Modified"] =
-                            crow::utility::getDateTime(updateTimestamp);
+                            crow::utility::getDateTimeStdtime(updateTimestamp);
                         if (filePath != nullptr)
                         {
                             thisEntry["AdditionalDataURI"] =
@@ -1628,9 +1626,9 @@
                         asyncResp->res.jsonValue["Severity"] =
                             translateSeverityDbusToRedfish(*severity);
                         asyncResp->res.jsonValue["Created"] =
-                            crow::utility::getDateTime(timestamp);
+                            crow::utility::getDateTimeStdtime(timestamp);
                         asyncResp->res.jsonValue["Modified"] =
-                            crow::utility::getDateTime(updateTimestamp);
+                            crow::utility::getDateTimeStdtime(updateTimestamp);
                         if (filePath != nullptr)
                         {
                             asyncResp->res.jsonValue["AdditionalDataURI"] =
@@ -3154,8 +3152,8 @@
 
         // Get the Created time from the timestamp
         std::string entryTimeStr;
-        entryTimeStr = crow::utility::getDateTime(
-            static_cast<std::time_t>(usecSinceEpoch / 1000 / 1000));
+        entryTimeStr =
+            crow::utility::getDateTimeUint(usecSinceEpoch / 1000 / 1000);
 
         // assemble messageArgs: BootIndex, TimeOffset(100us), PostCode(hex)
         std::ostringstream hexCode;
diff --git a/redfish-core/lib/managers.hpp b/redfish-core/lib/managers.hpp
index 12af99d..ca5d8c5 100644
--- a/redfish-core/lib/managers.hpp
+++ b/redfish-core/lib/managers.hpp
@@ -1739,12 +1739,11 @@
             }
             // LastRebootTime is epoch time, in milliseconds
             // https://github.com/openbmc/phosphor-dbus-interfaces/blob/7f9a128eb9296e926422ddc312c148b625890bb6/xyz/openbmc_project/State/BMC.interface.yaml#L19
-            time_t lastResetTimeStamp =
-                static_cast<time_t>(*lastResetTimePtr / 1000);
+            uint64_t lastResetTimeStamp = *lastResetTimePtr / 1000;
 
             // Convert to ISO 8601 standard
             aResp->res.jsonValue["LastResetTime"] =
-                crow::utility::getDateTime(lastResetTimeStamp);
+                crow::utility::getDateTimeUint(lastResetTimeStamp);
         },
         "xyz.openbmc_project.State.BMC", "/xyz/openbmc_project/state/bmc0",
         "org.freedesktop.DBus.Properties", "Get",
diff --git a/redfish-core/lib/metric_report.hpp b/redfish-core/lib/metric_report.hpp
index c959495..5ecab77 100644
--- a/redfish-core/lib/metric_report.hpp
+++ b/redfish-core/lib/metric_report.hpp
@@ -26,8 +26,7 @@
             {"MetricId", id},
             {"MetricProperty", metadata},
             {"MetricValue", std::to_string(sensorValue)},
-            {"Timestamp",
-             crow::utility::getDateTime(static_cast<time_t>(timestamp))},
+            {"Timestamp", crow::utility::getDateTimeUint(timestamp)},
         });
     }
 
@@ -53,8 +52,7 @@
     }
 
     const auto& [timestamp, readings] = *timestampReadings;
-    json["Timestamp"] =
-        crow::utility::getDateTime(static_cast<time_t>(timestamp));
+    json["Timestamp"] = crow::utility::getDateTimeUint(timestamp);
     json["MetricValues"] = toMetricValues(readings);
     return true;
 }
diff --git a/redfish-core/lib/systems.hpp b/redfish-core/lib/systems.hpp
index 2f88a77..8e1a6f4 100644
--- a/redfish-core/lib/systems.hpp
+++ b/redfish-core/lib/systems.hpp
@@ -1171,12 +1171,11 @@
             }
             // LastStateChangeTime is epoch time, in milliseconds
             // https://github.com/openbmc/phosphor-dbus-interfaces/blob/33e8e1dd64da53a66e888d33dc82001305cd0bf9/xyz/openbmc_project/State/Chassis.interface.yaml#L19
-            time_t lastResetTimeStamp =
-                static_cast<time_t>(*lastResetTimePtr / 1000);
+            uint64_t lastResetTimeStamp = *lastResetTimePtr / 1000;
 
             // Convert to ISO 8601 standard
             aResp->res.jsonValue["LastResetTime"] =
-                crow::utility::getDateTime(lastResetTimeStamp);
+                crow::utility::getDateTimeUint(lastResetTimeStamp);
         },
         "xyz.openbmc_project.State.Chassis",
         "/xyz/openbmc_project/state/chassis0",
diff --git a/redfish-core/lib/task.hpp b/redfish-core/lib/task.hpp
index 22e9743..b7795a7 100644
--- a/redfish-core/lib/task.hpp
+++ b/redfish-core/lib/task.hpp
@@ -388,11 +388,11 @@
                 asyncResp->res.jsonValue["Name"] = "Task " + strParam;
                 asyncResp->res.jsonValue["TaskState"] = ptr->state;
                 asyncResp->res.jsonValue["StartTime"] =
-                    crow::utility::getDateTime(ptr->startTime);
+                    crow::utility::getDateTimeStdtime(ptr->startTime);
                 if (ptr->endTime)
                 {
                     asyncResp->res.jsonValue["EndTime"] =
-                        crow::utility::getDateTime(*(ptr->endTime));
+                        crow::utility::getDateTimeStdtime(*(ptr->endTime));
                 }
                 asyncResp->res.jsonValue["TaskStatus"] = ptr->status;
                 asyncResp->res.jsonValue["Messages"] = ptr->messages;