diff --git a/src/chainparams.cpp b/src/chainparams.cpp
index 4735adc75..00307f72a 100644
--- a/src/chainparams.cpp
+++ b/src/chainparams.cpp
@@ -101,7 +101,7 @@ public:
         pchMessageStart[3] = 0xbd;
         vAlertPubKey = ParseHex("048240a8748a80a286b270ba126705ced4f2ce5a7847b3610ea3c06513150dade2a8512ed5ea86320824683fc0818f0ac019214973e677acd1244f6d0571fc5103");
         nDefaultPort = 9999;
-        nMaxTipAge = 24 * 60 * 60;
+        nMaxTipAge = 6 * 60 * 60; // ~144 blocks behind -> 2 x fork detection time, was 24 * 60 * 60 in bitcoin
         nPruneAfterHeight = 100000;
 
         genesis = CreateGenesisBlock(1390095618, 28917698, 0x1e0ffff0, 1, 50 * COIN);
@@ -206,7 +206,7 @@ public:
         pchMessageStart[3] = 0xff;
         vAlertPubKey = ParseHex("04517d8a699cb43d3938d7b24faaff7cda448ca4ea267723ba614784de661949bf632d6304316b244646dea079735b9a6fc4af804efb4752075b9fe2245e14e412");
         nDefaultPort = 19999;
-        nMaxTipAge = 0x7fffffff;
+        nMaxTipAge = 0x7fffffff; // allow mining on top of old blocks for testnet
         nPruneAfterHeight = 1000;
 
         genesis = CreateGenesisBlock(1390666206, 3861367235, 0x1e0ffff0, 1, 50 * COIN);
@@ -291,7 +291,7 @@ public:
         pchMessageStart[1] = 0xc1;
         pchMessageStart[2] = 0xb7;
         pchMessageStart[3] = 0xdc;
-        nMaxTipAge = 24 * 60 * 60;
+        nMaxTipAge = 6 * 60 * 60; // ~144 blocks behind -> 2 x fork detection time, was 24 * 60 * 60 in bitcoin
         nDefaultPort = 19994;
         nPruneAfterHeight = 1000;
 
diff --git a/src/main.cpp b/src/main.cpp
index 3eab8ffcf..15860c0d1 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -1592,7 +1592,7 @@ bool IsInitialBlockDownload()
     if (lockIBDState)
         return false;
     bool state = (chainActive.Height() < pindexBestHeader->nHeight - 24 * 6 ||
-            pindexBestHeader->GetBlockTime() < GetTime() - chainParams.MaxTipAge()); // TODO: was 6 * 60 * 60); // ~144 blocks behind -> 2 x fork detection time
+            pindexBestHeader->GetBlockTime() < GetTime() - chainParams.MaxTipAge());
     if (!state)
         lockIBDState = true;
     return state;