diff --git a/src/rpcblockchain.cpp b/src/rpcblockchain.cpp
index f66b1b204..f280cfc72 100644
--- a/src/rpcblockchain.cpp
+++ b/src/rpcblockchain.cpp
@@ -1410,16 +1410,18 @@ UniValue getchaintips(const UniValue& params, bool fHelp)
             + HelpExampleRpc("getchaintips", "")
         );
 
+    if ( mapBlockIndex == 0 )
+        throw runtime_error("mapBlockIndex is NULL\n");
     LOCK(cs_main);
 
     /* Build up a list of chain tips.  We start with the list of all
        known blocks, and successively remove blocks that appear as pprev
        of another block.  */
+    
     std::set<const CBlockIndex*, CompareBlocksByHeight> setTips;
     BOOST_FOREACH(const PAIRTYPE(const uint256, CBlockIndex*)& item, mapBlockIndex)
     {
-        if ( item != 0 )
-            setTips.insert(item.second);
+        setTips.insert(item.second);
     }
     BOOST_FOREACH(const PAIRTYPE(const uint256, CBlockIndex*)& item, mapBlockIndex)
     {