diff --git a/lib/cpp/src/thrift/protocol/TJSONProtocol.cpp b/lib/cpp/src/thrift/protocol/TJSONProtocol.cpp
index 412e927..31ebb3c 100644
--- a/lib/cpp/src/thrift/protocol/TJSONProtocol.cpp
+++ b/lib/cpp/src/thrift/protocol/TJSONProtocol.cpp
@@ -651,7 +651,9 @@
 }
 
 uint32_t TJSONProtocol::writeMapEnd() {
-  return writeJSONObjectEnd() + writeJSONArrayEnd();
+  uint32_t result = writeJSONObjectEnd();
+  result += writeJSONArrayEnd();
+  return result;
 }
 
 uint32_t TJSONProtocol::writeListBegin(const TType elemType, const uint32_t size) {
@@ -1015,7 +1017,9 @@
 }
 
 uint32_t TJSONProtocol::readMapEnd() {
-  return readJSONObjectEnd() + readJSONArrayEnd();
+  uint32_t result = readJSONObjectEnd();
+  result += readJSONArrayEnd();
+  return result;
 }
 
 uint32_t TJSONProtocol::readListBegin(TType& elemType, uint32_t& size) {