diff --git a/CMakeLists.txt b/CMakeLists.txt
index 49b665d..1121345 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -9,9 +9,11 @@ option(toml11_TEST_WITH_UBSAN "use LLVM undefined behavior sanitizer" OFF)
 
 include(CheckCXXCompilerFlag)
 if("${CMAKE_VERSION}" VERSION_GREATER 3.1)
-    set(CMAKE_CXX_STANDARD 11 CACHE STRING "The C++ standard whose features are requested to build all targets.")
-    set(CMAKE_CXX_STANDARD_REQUIRED ON CACHE BOOL "Boolean describing whether the value of CXX_STANDARD is a requirement.")
     set(CMAKE_CXX_EXTENSIONS OFF CACHE BOOL "Boolean specifying whether compiler specific extensions are requested.")
+    if(NOT DEFINED CMAKE_CXX_STANDARD)
+        set(CMAKE_CXX_STANDARD 11 CACHE STRING "The C++ standard whose features are requested to build all targets.")
+    endif()
+    set(CMAKE_CXX_STANDARD_REQUIRED ON CACHE BOOL "Boolean describing whether the value of CXX_STANDARD is a requirement.")
 else()
     # Manually check for C++11 compiler flag.
     CHECK_CXX_COMPILER_FLAG("-std=c++11" COMPILER_SUPPORTS_CXX11)
diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index 49ebcb4..99d73b9 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -149,6 +149,10 @@ if(MSVC)
     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /wd4820")
     # pragma warning(pop): likely mismatch, popping warning state pushed in different file
     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /wd5031")
+	# pragma warning(pop): spectre warnings in tests
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /wd5045")
+	# pragma warning(pop): spectre warnings in tests
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /wd4265")
 endif()
 
 find_package(Boost COMPONENTS unit_test_framework REQUIRED)
@@ -185,6 +189,7 @@ option(TOML11_REQUIRE_FILESYSTEM_LIBRARY "need to link -lstdc++fs or -lc++fs" OF
 foreach(TEST_NAME ${TEST_NAMES})
     add_executable(${TEST_NAME} ${TEST_NAME}.cpp)
     target_link_libraries(${TEST_NAME} ${Boost_UNIT_TEST_FRAMEWORK_LIBRARY} toml11::toml11)
+    target_include_directories(${TEST_NAME} SYSTEM PRIVATE ${Boost_INCLUDE_DIRS})
 
     # to compile tests with <filesystem>...
     if(TOML11_REQUIRE_FILESYSTEM_LIBRARY)
diff --git a/toml/get.hpp b/toml/get.hpp
index 6669e34..d7fdf55 100644
--- a/toml/get.hpp
+++ b/toml/get.hpp
@@ -140,7 +140,7 @@ get(basic_value<C, M, V>&& v)
 // ============================================================================
 // std::string_view
 
-#if __cplusplus >= 201703L
+#if defined(TOML11_USING_STRING_VIEW) && TOML11_USING_STRING_VIEW>0
 template<typename T, typename C,
          template<typename ...> class M, template<typename ...> class V>
 inline detail::enable_if_t<std::is_same<T, std::string_view>::value, std::string_view>
diff --git a/toml/string.hpp b/toml/string.hpp
index a6ed080..5136d8c 100644
--- a/toml/string.hpp
+++ b/toml/string.hpp
@@ -9,6 +9,7 @@
 
 #if __cplusplus >= 201703L
 #if __has_include(<string_view>)
+#define TOML11_USING_STRING_VIEW 1
 #include <string_view>
 #endif
 #endif
@@ -53,7 +54,7 @@ struct string
     string& operator+=(const std::string& rhs) {str += rhs; return *this;}
     string& operator+=(const string&      rhs) {str += rhs.str; return *this;}
 
-#if __cplusplus >= 201703L
+#if defined(TOML11_USING_STRING_VIEW) && TOML11_USING_STRING_VIEW>0
     explicit string(std::string_view s): kind(string_t::basic), str(s){}
     string(std::string_view s, string_t k): kind(k), str(s){}
 
diff --git a/toml/traits.hpp b/toml/traits.hpp
index 0064e37..5495c93 100644
--- a/toml/traits.hpp
+++ b/toml/traits.hpp
@@ -209,7 +209,9 @@ struct is_container : conjunction<
     negation<is_map<T>>,                         // not a map
     negation<std::is_same<T, std::string>>,      // not a std::string
 #if __cplusplus >= 201703L
+#if __has_include(<string_view>)
     negation<std::is_same<T, std::string_view>>, // not a std::string_view
+#endif // has_include(<string_view>)
 #endif
     has_iterator<T>,                             // has T::iterator
     has_value_type<T>                            // has T::value_type
@@ -280,7 +282,7 @@ using enable_if_t = typename std::enable_if<B, T>::type;
 // ---------------------------------------------------------------------------
 // return_type_of_t
 
-#if __cplusplus >= 201703L
+#if __cplusplus >= 201703L && defined(__cpp_lib_is_invocable) && __cpp_lib_is_invocable>=201703
 
 template<typename F, typename ... Args>
 using return_type_of_t = std::invoke_result_t<F, Args...>;
diff --git a/toml/value.hpp b/toml/value.hpp
index ecae2c3..1b43db8 100644
--- a/toml/value.hpp
+++ b/toml/value.hpp
@@ -624,7 +624,7 @@ class basic_value
         assigner(this->string_, toml::string(std::string(s), kind));
     }
 
-#if __cplusplus >= 201703L
+#if defined(TOML11_USING_STRING_VIEW) && TOML11_USING_STRING_VIEW>0
     basic_value(std::string_view s)
         : type_(value_t::string),
           region_info_(std::make_shared<region_base>(region_base{}))