diff --git a/src/wallet/wallet.cpp b/src/wallet/wallet.cpp
index 186d3c5cd..d415bb09c 100644
--- a/src/wallet/wallet.cpp
+++ b/src/wallet/wallet.cpp
@@ -2263,7 +2263,9 @@ bool CWallet::SignTransaction(CMutableTransaction &tx)
     int nIn = 0;
     for (auto& input : tx.vin) {
         std::map<uint256, CWalletTx>::const_iterator mi = mapWallet.find(input.prevout.hash);
-        assert(mi != mapWallet.end() && input.prevout.n < mi->second.tx->vout.size());
+        if(mi == mapWallet.end() || input.prevout.n >= mi->second.tx->vout.size()) {
+            return false;
+        }
         const CScript& scriptPubKey = mi->second.tx->vout[input.prevout.n].scriptPubKey;
         const CAmount& amount = mi->second.tx->vout[input.prevout.n].nValue;
         SignatureData sigdata;