diff --git a/src/ripple_net/rpc/RPCCall.cpp b/src/ripple_net/rpc/RPCCall.cpp
index f8950df34..87ab1c8e9 100644
--- a/src/ripple_net/rpc/RPCCall.cpp
+++ b/src/ripple_net/rpc/RPCCall.cpp
@@ -407,6 +407,9 @@ private:
 
         if (reader.parse (jvParams[1u].asString (), jvRequest))
         {
+            if (!jvRequest.isObject ())
+                return rpcError (rpcINVALID_PARAMS);
+
             jvRequest["method"] = jvParams[0u];
 
             return jvRequest;