diff --git a/src/rpc/server.cpp b/src/rpc/server.cpp
index 1b94e1007..283d458c8 100644
--- a/src/rpc/server.cpp
+++ b/src/rpc/server.cpp
@@ -79,16 +79,20 @@ void RPCTypeCheck(const UniValue& params,
             break;
 
         const UniValue& v = params[i];
-        if (!((v.type() == t) || (fAllowNull && (v.isNull()))))
-        {
-            string err = strprintf("Expected type %s, got %s",
-                                   uvTypeName(t), uvTypeName(v.type()));
-            throw JSONRPCError(RPC_TYPE_ERROR, err);
+        if (!(fAllowNull && v.isNull())) {
+            RPCTypeCheckArgument(v, t);
         }
         i++;
     }
 }
 
+void RPCTypeCheckArgument(const UniValue& value, UniValue::VType typeExpected)
+{
+    if (value.type() != typeExpected) {
+        throw JSONRPCError(RPC_TYPE_ERROR, strprintf("Expected type %s, got %s", uvTypeName(typeExpected), uvTypeName(value.type())));
+    }
+}
+
 void RPCTypeCheckObj(const UniValue& o,
     const map<string, UniValueType>& typesExpected,
     bool fAllowNull,
diff --git a/src/rpc/server.h b/src/rpc/server.h
index fed3d8c90..52f82866d 100644
--- a/src/rpc/server.h
+++ b/src/rpc/server.h
@@ -78,6 +78,11 @@ bool RPCIsInWarmup(std::string *statusOut);
 void RPCTypeCheck(const UniValue& params,
                   const std::list<UniValue::VType>& typesExpected, bool fAllowNull=false);
 
+/**
+ * Type-check one argument; throws JSONRPCError if wrong type given.
+ */
+void RPCTypeCheckArgument(const UniValue& value, UniValue::VType typeExpected);
+
 /*
   Check for expected keys/value types in an Object.
 */
diff --git a/src/wallet/rpcwallet.cpp b/src/wallet/rpcwallet.cpp
index 4dda48021..ffe0827be 100644
--- a/src/wallet/rpcwallet.cpp
+++ b/src/wallet/rpcwallet.cpp
@@ -2350,9 +2350,9 @@ UniValue listunspent(const JSONRPCRequest& request)
     if (!EnsureWalletIsAvailable(request.fHelp))
         return NullUniValue;
 
-    if (request.fHelp || request.params.size() > 3)
+    if (request.fHelp || request.params.size() > 4)
         throw runtime_error(
-            "listunspent ( minconf maxconf  [\"addresses\",...] )\n"
+            "listunspent ( minconf maxconf  [\"addresses\",...] [include_unsafe] )\n"
             "\nReturns array of unspent transaction outputs\n"
             "with between minconf and maxconf (inclusive) confirmations.\n"
             "Optionally filter to only include txouts paid to specified addresses.\n"
@@ -2364,6 +2364,10 @@ UniValue listunspent(const JSONRPCRequest& request)
             "      \"address\"   (string) bitcoin address\n"
             "      ,...\n"
             "    ]\n"
+            "4. include_unsafe (bool, optional, default=true) Include outputs that are not safe to spend\n"
+            "                  because they come from unconfirmed untrusted transactions or unconfirmed\n"
+            "                  replacement transactions (cases where we are less sure that a conflicting\n"
+            "                  transaction won't be mined).\n"
             "\nResult\n"
             "[                   (array of json object)\n"
             "  {\n"
@@ -2387,18 +2391,21 @@ UniValue listunspent(const JSONRPCRequest& request)
             + HelpExampleRpc("listunspent", "6, 9999999 \"[\\\"1PGFqEzfmQch1gKD3ra4k18PNj3tTUUSqg\\\",\\\"1LtvqCaApEdUGFkpKMM4MstjcaL4dKg8SP\\\"]\"")
         );
 
-    RPCTypeCheck(request.params, boost::assign::list_of(UniValue::VNUM)(UniValue::VNUM)(UniValue::VARR));
-
     int nMinDepth = 1;
-    if (request.params.size() > 0)
+    if (request.params.size() > 0 && !request.params[0].isNull()) {
+        RPCTypeCheckArgument(request.params[0], UniValue::VNUM);
         nMinDepth = request.params[0].get_int();
+    }
 
     int nMaxDepth = 9999999;
-    if (request.params.size() > 1)
+    if (request.params.size() > 1 && !request.params[1].isNull()) {
+        RPCTypeCheckArgument(request.params[1], UniValue::VNUM);
         nMaxDepth = request.params[1].get_int();
+    }
 
     set<CBitcoinAddress> setAddress;
-    if (request.params.size() > 2) {
+    if (request.params.size() > 2 && !request.params[2].isNull()) {
+        RPCTypeCheckArgument(request.params[2], UniValue::VARR);
         UniValue inputs = request.params[2].get_array();
         for (unsigned int idx = 0; idx < inputs.size(); idx++) {
             const UniValue& input = inputs[idx];
@@ -2411,11 +2418,17 @@ UniValue listunspent(const JSONRPCRequest& request)
         }
     }
 
+    bool include_unsafe = true;
+    if (request.params.size() > 3 && !request.params[3].isNull()) {
+        RPCTypeCheckArgument(request.params[3], UniValue::VBOOL);
+        include_unsafe = request.params[3].get_bool();
+    }
+
     UniValue results(UniValue::VARR);
     vector<COutput> vecOutputs;
     assert(pwalletMain != NULL);
     LOCK2(cs_main, pwalletMain->cs_wallet);
-    pwalletMain->AvailableCoins(vecOutputs, false, NULL, true);
+    pwalletMain->AvailableCoins(vecOutputs, !include_unsafe, NULL, true);
     BOOST_FOREACH(const COutput& out, vecOutputs) {
         if (out.nDepth < nMinDepth || out.nDepth > nMaxDepth)
             continue;
@@ -2629,7 +2642,7 @@ static const CRPCCommand commands[] =
     { "wallet",             "listreceivedbyaddress",    &listreceivedbyaddress,    false,  {"minconf","include_empty","include_watchonly"} },
     { "wallet",             "listsinceblock",           &listsinceblock,           false,  {"blockhash","target_confirmations","include_watchonly"} },
     { "wallet",             "listtransactions",         &listtransactions,         false,  {"account","count","skip","include_watchonly"} },
-    { "wallet",             "listunspent",              &listunspent,              false,  {"minconf","maxconf","addresses"} },
+    { "wallet",             "listunspent",              &listunspent,              false,  {"minconf","maxconf","addresses","include_unsafe"} },
     { "wallet",             "lockunspent",              &lockunspent,              true,   {"unlock","transactions"} },
     { "wallet",             "move",                     &movecmd,                  false,  {"fromaccount","toaccount","amount","minconf","comment"} },
     { "wallet",             "sendfrom",                 &sendfrom,                 false,  {"fromaccount","toaddress","amount","minconf","comment","comment_to"} },