diff --git a/src/init.cpp b/src/init.cpp
index 7f311fa88..74533e49e 100644
--- a/src/init.cpp
+++ b/src/init.cpp
@@ -571,7 +571,7 @@ bool AppInit2()
     printf("Bitcoin version %s (%s)\n", FormatFullVersion().c_str(), CLIENT_DATE.c_str());
     printf("Using OpenSSL version %s\n", SSLeay_version(SSLEAY_VERSION));
     if (!fLogTimestamps)
-        printf("Startup time: %s\n", DateTimeStrFormat("%x %H:%M:%S", GetTime()).c_str());
+        printf("Startup time: %s\n", DateTimeStrFormat("%Y-%m-%dT%H:%M:%S", GetTime()).c_str());
     printf("Default data directory %s\n", GetDefaultDataDir().string().c_str());
     printf("Used data directory %s\n", strDataDir.c_str());
     std::ostringstream strErrors;
diff --git a/src/main.cpp b/src/main.cpp
index 61bd6b7b8..96bdabd58 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -1187,11 +1187,11 @@ void static InvalidChainFound(CBlockIndex* pindexNew)
     }
     printf("InvalidChainFound: invalid block=%s  height=%d  work=%s  date=%s\n",
       BlockHashStr(pindexNew->GetBlockHash()).c_str(), pindexNew->nHeight,
-      pindexNew->bnChainWork.ToString().c_str(), DateTimeStrFormat("%x %H:%M:%S",
+      pindexNew->bnChainWork.ToString().c_str(), DateTimeStrFormat("%Y-%m-%dT%H:%M:%S",
       pindexNew->GetBlockTime()).c_str());
     printf("InvalidChainFound:  current best=%s  height=%d  work=%s  date=%s\n",
       BlockHashStr(hashBestChain).c_str(), nBestHeight, bnBestChainWork.ToString().c_str(),
-      DateTimeStrFormat("%x %H:%M:%S", pindexBest->GetBlockTime()).c_str());
+      DateTimeStrFormat("%Y-%m-%dT%H:%M:%S", pindexBest->GetBlockTime()).c_str());
     if (pindexBest && bnBestInvalidWork > bnBestChainWork + pindexBest->GetBlockWork() * 6)
         printf("InvalidChainFound: Warning: Displayed transactions may not be correct! You may need to upgrade, or other nodes may need to upgrade.\n");
 }
@@ -1828,7 +1828,7 @@ bool SetBestChain(CBlockIndex* pindexNew)
     nTransactionsUpdated++;
     printf("SetBestChain: new best=%s  height=%d  work=%s  tx=%lu  date=%s\n",
       BlockHashStr(hashBestChain).c_str(), nBestHeight, bnBestChainWork.ToString().c_str(), (unsigned long)pindexNew->nChainTx,
-      DateTimeStrFormat("%x %H:%M:%S", pindexBest->GetBlockTime()).c_str());
+      DateTimeStrFormat("%Y-%m-%dT%H:%M:%S", pindexBest->GetBlockTime()).c_str());
 
     // Check the version of the last 100 blocks to see if we need to upgrade:
     if (!fIsInitialDownload)
@@ -2375,7 +2375,7 @@ bool static LoadBlockIndexDB()
     }
     printf("LoadBlockIndex(): hashBestChain=%s  height=%d date=%s\n",
         BlockHashStr(hashBestChain).c_str(), nBestHeight,
-        DateTimeStrFormat("%x %H:%M:%S", pindexBest->GetBlockTime()).c_str());
+        DateTimeStrFormat("%Y-%m-%dT%H:%M:%S", pindexBest->GetBlockTime()).c_str());
 
     // Verify blocks in the best chain
     int nCheckLevel = GetArg("-checklevel", 1);
@@ -2538,7 +2538,7 @@ void PrintBlockTree()
         printf("%d (blk%05u.dat:0x%x)  %s  tx %"PRIszu"",
             pindex->nHeight,
             pindex->GetBlockPos().nFile, pindex->GetBlockPos().nPos,
-            DateTimeStrFormat("%x %H:%M:%S", block.GetBlockTime()).c_str(),
+            DateTimeStrFormat("%Y-%m-%dT%H:%M:%S", block.GetBlockTime()).c_str(),
             block.vtx.size());
 
         PrintWallets(block);
diff --git a/src/test/util_tests.cpp b/src/test/util_tests.cpp
index 3a4c035a3..c47d25bbe 100644
--- a/src/test/util_tests.cpp
+++ b/src/test/util_tests.cpp
@@ -104,11 +104,11 @@ BOOST_AUTO_TEST_CASE(util_HexStr)
 BOOST_AUTO_TEST_CASE(util_DateTimeStrFormat)
 {
 /*These are platform-dependant and thus removed to avoid useless test failures
-    BOOST_CHECK_EQUAL(DateTimeStrFormat("%x %H:%M:%S", 0), "01/01/70 00:00:00");
-    BOOST_CHECK_EQUAL(DateTimeStrFormat("%x %H:%M:%S", 0x7FFFFFFF), "01/19/38 03:14:07");
+    BOOST_CHECK_EQUAL(DateTimeStrFormat("%Y-%m-%dT%H:%M:%S", 0), "1970-01-01T00:00:00");
+    BOOST_CHECK_EQUAL(DateTimeStrFormat("%Y-%m-%dT%H:%M:%S", 0x7FFFFFFF), "2038-01-19T03:14:07");
     // Formats used within Bitcoin
-    BOOST_CHECK_EQUAL(DateTimeStrFormat("%x %H:%M:%S", 1317425777), "09/30/11 23:36:17");
-    BOOST_CHECK_EQUAL(DateTimeStrFormat("%x %H:%M", 1317425777), "09/30/11 23:36");
+    BOOST_CHECK_EQUAL(DateTimeStrFormat("%Y-%m-%dT%H:%M:%S", 1317425777), "2011-09-30T23:36:17");
+    BOOST_CHECK_EQUAL(DateTimeStrFormat("%Y-%m-%dT%H:%M", 1317425777), "2011-09-30T23:36");
 */
 }
 
diff --git a/src/util.cpp b/src/util.cpp
index 3cbc6b196..806f3ebcf 100644
--- a/src/util.cpp
+++ b/src/util.cpp
@@ -240,7 +240,7 @@ inline int OutputDebugStringF(const char* pszFormat, ...)
 
             // Debug print useful for profiling
             if (fLogTimestamps && fStartedNewLine)
-                fprintf(fileout, "%s ", DateTimeStrFormat("%x %H:%M:%S", GetTime()).c_str());
+                fprintf(fileout, "%s ", DateTimeStrFormat("%Y-%m-%dT%H:%M:%S", GetTime()).c_str());
             if (pszFormat[strlen(pszFormat) - 1] == '\n')
                 fStartedNewLine = true;
             else
diff --git a/src/walletdb.cpp b/src/walletdb.cpp
index e102df972..4419cbb5f 100644
--- a/src/walletdb.cpp
+++ b/src/walletdb.cpp
@@ -238,7 +238,7 @@ ReadKeyValue(CWallet* pwallet, CDataStream& ssKey, CDataStream& ssValue,
             //printf("LoadWallet  %s\n", wtx.GetHash().ToString().c_str());
             //printf(" %12"PRI64d"  %s  %s  %s\n",
             //    wtx.vout[0].nValue,
-            //    DateTimeStrFormat("%x %H:%M:%S", wtx.GetBlockTime()).c_str(),
+            //    DateTimeStrFormat("%Y-%m-%dT%H:%M:%S", wtx.GetBlockTime()).c_str(),
             //    wtx.hashBlock.ToString().substr(0,20).c_str(),
             //    wtx.mapValue["message"].c_str());
         }