diff --git a/src/wallet/asyncrpcoperation_sendmany.cpp b/src/wallet/asyncrpcoperation_sendmany.cpp
index 8ba40928e..3d2675a92 100644
--- a/src/wallet/asyncrpcoperation_sendmany.cpp
+++ b/src/wallet/asyncrpcoperation_sendmany.cpp
@@ -593,6 +593,10 @@ bool AsyncRPCOperation_sendmany::main_impl() {
             {
                 LOCK2(cs_main, pwalletMain->cs_wallet);
                 const CWalletTx& wtx = pwalletMain->mapWallet[jso.hash];
+                // Zero confirmaton notes belong to transactions which have not yet been mined
+                if (mapBlockIndex.find(wtx.hashBlock) == mapBlockIndex.end()) {
+                    throw JSONRPCError(RPC_WALLET_ERROR, strprintf("mapBlockIndex does not contain block hash %s", wtx.hashBlock.ToString()));
+                }
                 wtxHeight = mapBlockIndex[wtx.hashBlock]->nHeight;
                 wtxDepth = wtx.GetDepthInMainChain();
             }