diff --git a/src/rpc/mining.cpp b/src/rpc/mining.cpp
index b823c159d..cfa6edae1 100644
--- a/src/rpc/mining.cpp
+++ b/src/rpc/mining.cpp
@@ -744,6 +744,10 @@ UniValue submitblock(const JSONRPCRequest& request)
     if (!DecodeHexBlk(block, request.params[0].get_str()))
         throw JSONRPCError(RPC_DESERIALIZATION_ERROR, "Block decode failed");
 
+    if (block.vtx.empty() || !block.vtx[0]->IsCoinBase()) {
+        throw JSONRPCError(RPC_DESERIALIZATION_ERROR, "Block does not start with a coinbase");
+    }
+
     uint256 hash = block.GetHash();
     bool fBlockPresent = false;
     {