diff --git a/CMakeLists.txt b/CMakeLists.txt
index c0f940467630..7d2c3aa7e65b 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -23,7 +23,7 @@ endif()
 
 project(torch-mlir LANGUAGES CXX C)
 set(CMAKE_C_STANDARD 11)
-set(CMAKE_CXX_STANDARD 17)
+set(CMAKE_CXX_STANDARD 17 CACHE STRING "C++ standard to use")
 
 include(CMakeDependentOption)
 
diff --git a/lib/RefBackend/RefBackend.cpp b/lib/RefBackend/RefBackend.cpp
index d40d02d43ffc..cd2413234857 100644
--- a/lib/RefBackend/RefBackend.cpp
+++ b/lib/RefBackend/RefBackend.cpp
@@ -109,7 +109,7 @@ static std::string getConsumeReturnFunctionNameForReturnTypes(TypeRange types) {
     tokens.push_back(getTypeToken(type));
 
   return std::accumulate(tokens.begin(), tokens.end(), std::string(),
-                         [](std::string &a, std::string &b) {
+                         [](const std::string &a, const std::string &b) {
                            return a.empty() ? b : (a + "_" + b);
                          });
 }