diff --git a/src/main.cpp b/src/main.cpp
index 520d1ab87c..8103c8ad82 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -2103,18 +2103,24 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv)
         CAddress addrFrom;
         uint64 nNonce = 1;
         vRecv >> pfrom->nVersion >> pfrom->nServices >> nTime >> addrMe;
+        if (pfrom->nVersion < 209)
+        {
+            // Since Februari 20, 2012, the protocol is initiated at version 209,
+            // and earlier versions are no longer supported
+            printf("partner %s using obsolete version %i; disconnecting\n", pfrom->addr.ToString().c_str(), pfrom->nVersion);
+            pfrom->fDisconnect = true;
+            return false;
+        }
+
         if (pfrom->nVersion == 10300)
             pfrom->nVersion = 300;
-        if (pfrom->nVersion >= 106 && !vRecv.empty())
+        if (!vRecv.empty())
             vRecv >> addrFrom >> nNonce;
-        if (pfrom->nVersion >= 106 && !vRecv.empty())
+        if (!vRecv.empty())
             vRecv >> pfrom->strSubVer;
-        if (pfrom->nVersion >= 209 && !vRecv.empty())
+        if (!vRecv.empty())
             vRecv >> pfrom->nStartingHeight;
 
-        if (pfrom->nVersion == 0)
-            return false;
-
         // Disconnect if we connected to ourself
         if (nNonce == nLocalHostNonce && nNonce > 1)
         {
@@ -2132,11 +2138,8 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv)
         AddTimeData(pfrom->addr, nTime);
 
         // Change version
-        if (pfrom->nVersion >= 209)
-            pfrom->PushMessage("verack");
+        pfrom->PushMessage("verack");
         pfrom->vSend.SetVersion(min(pfrom->nVersion, PROTOCOL_VERSION));
-        if (pfrom->nVersion < 209)
-            pfrom->vRecv.SetVersion(min(pfrom->nVersion, PROTOCOL_VERSION));
 
         if (!pfrom->fInbound)
         {
@@ -2200,8 +2203,6 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv)
         vRecv >> vAddr;
 
         // Don't want addr from older versions unless seeding
-        if (pfrom->nVersion < 209)
-            return true;
         if (pfrom->nVersion < 31402 && mapAddresses.size() > 1000)
             return true;
         if (vAddr.size() > 1000)
@@ -2663,17 +2664,14 @@ bool ProcessMessages(CNode* pfrom)
         }
 
         // Checksum
-        if (vRecv.GetVersion() >= 209)
+        uint256 hash = Hash(vRecv.begin(), vRecv.begin() + nMessageSize);
+        unsigned int nChecksum = 0;
+        memcpy(&nChecksum, &hash, sizeof(nChecksum));
+        if (nChecksum != hdr.nChecksum)
         {
-            uint256 hash = Hash(vRecv.begin(), vRecv.begin() + nMessageSize);
-            unsigned int nChecksum = 0;
-            memcpy(&nChecksum, &hash, sizeof(nChecksum));
-            if (nChecksum != hdr.nChecksum)
-            {
-                printf("ProcessMessage(%s, %u bytes) : CHECKSUM ERROR nChecksum=%08x hdr.nChecksum=%08x\n",
-                       strCommand.c_str(), nMessageSize, nChecksum, hdr.nChecksum);
-                continue;
-            }
+            printf("ProcessMessage(%s, %u bytes) : CHECKSUM ERROR nChecksum=%08x hdr.nChecksum=%08x\n",
+               strCommand.c_str(), nMessageSize, nChecksum, hdr.nChecksum);
+            continue;
         }
 
         // Copy message to its own buffer
diff --git a/src/net.h b/src/net.h
index f4af93a495..51a816d4d3 100644
--- a/src/net.h
+++ b/src/net.h
@@ -167,15 +167,9 @@ public:
         nServices = 0;
         hSocket = hSocketIn;
         vSend.SetType(SER_NETWORK);
-        vSend.SetVersion(0);
         vRecv.SetType(SER_NETWORK);
-        vRecv.SetVersion(0);
-        // Version 0.2 obsoletes 20 Feb 2012
-        if (GetTime() > 1329696000)
-        {
-            vSend.SetVersion(209);
-            vRecv.SetVersion(209);
-        }
+        vSend.SetVersion(209);
+        vRecv.SetVersion(209);
         nLastSend = 0;
         nLastRecv = 0;
         nLastSendEmpty = GetTime();
@@ -334,14 +328,11 @@ public:
         memcpy((char*)&vSend[nHeaderStart] + offsetof(CMessageHeader, nMessageSize), &nSize, sizeof(nSize));
 
         // Set the checksum
-        if (vSend.GetVersion() >= 209)
-        {
-            uint256 hash = Hash(vSend.begin() + nMessageStart, vSend.end());
-            unsigned int nChecksum = 0;
-            memcpy(&nChecksum, &hash, sizeof(nChecksum));
-            assert(nMessageStart - nHeaderStart >= offsetof(CMessageHeader, nChecksum) + sizeof(nChecksum));
-            memcpy((char*)&vSend[nHeaderStart] + offsetof(CMessageHeader, nChecksum), &nChecksum, sizeof(nChecksum));
-        }
+        uint256 hash = Hash(vSend.begin() + nMessageStart, vSend.end());
+        unsigned int nChecksum = 0;
+        memcpy(&nChecksum, &hash, sizeof(nChecksum));
+        assert(nMessageStart - nHeaderStart >= offsetof(CMessageHeader, nChecksum) + sizeof(nChecksum));
+        memcpy((char*)&vSend[nHeaderStart] + offsetof(CMessageHeader, nChecksum), &nChecksum, sizeof(nChecksum));
 
         if (fDebug) {
             printf("(%d bytes)\n", nSize);
diff --git a/src/protocol.h b/src/protocol.h
index 9ebbfad701..b70dd71b82 100644
--- a/src/protocol.h
+++ b/src/protocol.h
@@ -45,7 +45,6 @@ class CMessageHeader
              READWRITE(FLATDATA(pchMessageStart));
              READWRITE(FLATDATA(pchCommand));
              READWRITE(nMessageSize);
-             if (nVersion >= 209)
              READWRITE(nChecksum);
             )