diff --git a/src/sofa/pbrpc/pbjson.cc b/src/sofa/pbrpc/pbjson.cc
index 341a907..141c6e3 100644
--- a/src/sofa/pbrpc/pbjson.cc
+++ b/src/sofa/pbrpc/pbjson.cc
@@ -267,6 +267,11 @@ static rapidjson::Value* parse_msg(const Message *msg, rapidjson::Value::Allocat
         else
         {
             rapidjson::Value* field_json = field2json(msg, field, allocator);
+            if (!field_json)
+            {
+                delete root;
+                return NULL;
+            }
             root->AddMember(name, *field_json, allocator);
             delete field_json;
         }