diff --git a/CMakeLists.txt b/CMakeLists.txt
index d874adb..8a224e0 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -22,6 +22,8 @@ option(BUILD_TESTS "Enable testing" OFF)
 option(BUILD_HEADER_ONLY "Enable header only build" OFF)
 mark_as_advanced(ENABLE_PROFILING)
 
+set(CMAKE_CXX_STANDARD 20)
+
 set(LIBREXY_PUBLIC_HEADERS "include/rexy/rexy.hpp" "include/rexy/algorithm.hpp" "include/rexy/algorithm.tpp" "include/rexy/utility.hpp" "include/rexy/hash.hpp" "include/rexy/mpmc_queue.hpp" "include/rexy/mpmc_queue.tpp" "include/rexy/traits.hpp" "include/rexy/steal.hpp" "include/rexy/expression.hpp" "include/rexy/string_base.hpp" "include/rexy/string.hpp" "include/rexy/string_base.tpp" "include/rexy/allocator.hpp" "include/rexy/meta.hpp" "include/rexy/buffer.hpp" "include/rexy/buffer.tpp" "include/rexy/debug_print.hpp" "include/rexy/deferred.hpp" "include/rexy/enum_traits.hpp" "include/rexy/storage_for.hpp" "include/rexy/storage_for.tpp" "include/rexy/visitor.hpp" "include/rexy/string_view.hpp" "include/rexy/string_view.tpp" "include/rexy/format.hpp" "include/rexy/format.tpp")
 
 if(BUILD_HEADER_ONLY)
@@ -45,6 +47,12 @@ else()
 		set(LIBREXY_LIBFLAGS "-lrexy -lpthread")
 		target_link_libraries(rexy "-lpthread")
 	endif()
+
+	if(MSVC)
+		target_compile_options(rexy PRIVATE "/Zc:__cplusplus" "/Wall")
+	else()
+		target_compile_options(rexy PRIVATE "-Wall" "-Wextra" "-pedantic")
+	endif()
 	set_target_properties(rexy PROPERTIES VERSION "${librexy_VERSION_MAJOR}.${librexy_VERSION_MINOR}.${librexy_VERSION_REVISION}")
 
 	if(ENABLE_SSO)
@@ -57,12 +65,15 @@ else()
 		target_link_options(rexy PRIVATE -fsanitize=address -fno-omit-frame-pointer -fno-optimize-sibling-calls)
 	endif()
 
-	target_compile_options(rexy PRIVATE -Wall -Wextra -pedantic -std=c++20)
 endif()
 
 if(BUILD_TESTS)
 	add_library(ensure OBJECT "src/ensure.cpp")
-	target_compile_options(ensure PRIVATE -Wall -Wextra -pedantic -std=c++20)
+	if(MSVC)
+		target_compile_options(ensure PRIVATE "/Zc:__cplusplus" "/Wall")
+	else()
+		target_compile_options(ensure PRIVATE "-Wall" "-Wextra" "-pedantic")
+	endif()
 	enable_testing()
 	add_subdirectory(tests)
 endif()
diff --git a/include/rexy/compat/string_base.hpp b/include/rexy/compat/string_base.hpp
index 7a245d3..9b24501 100644
--- a/include/rexy/compat/string_base.hpp
+++ b/include/rexy/compat/string_base.hpp
@@ -22,7 +22,7 @@
 #include <cstddef> //size_t
 
 namespace rexy{
-	static constexpr std::size_t npos = std::size_t{-1};
+	static constexpr std::size_t npos = std::size_t(-1);
 }
 
 #ifdef __cpp_concepts
diff --git a/include/rexy/detail/format/basic_types.hpp b/include/rexy/detail/format/basic_types.hpp
index b6fe713..4db36b6 100644
--- a/include/rexy/detail/format/basic_types.hpp
+++ b/include/rexy/detail/format/basic_types.hpp
@@ -25,7 +25,7 @@
 
 namespace rexy::fmt::detail{
 
-	static constexpr std::size_t invalid_arg_index = std::size_t{-1};
+	static constexpr std::size_t invalid_arg_index = std::size_t(-1);
 
 
 	template<class Char>
diff --git a/include/rexy/detail/format/formatter.tpp b/include/rexy/detail/format/formatter.tpp
index 4259fe4..15ea065 100644
--- a/include/rexy/detail/format/formatter.tpp
+++ b/include/rexy/detail/format/formatter.tpp
@@ -328,9 +328,9 @@ namespace rexy::fmt::detail{
 		template<class Char, class OutIt>
 		constexpr OutIt perform_localized_integer_write(OutIt out, const char* start, const char* last, const std::locale& loc){
 			const auto& facet = std::use_facet<std::numpunct<Char>>(loc);
-			const int group_size = facet.grouping()[0];
+			const int group_size = int(facet.grouping()[0]);
 			const Char sep = facet.thousands_sep();
-			const int len = last - start;
+			const int len = int(last - start);
 			if(group_size != 0){
 				int write_count = (len-1) % group_size;
 				*out++ = *start++;
@@ -342,7 +342,7 @@ namespace rexy::fmt::detail{
 						break;
 					}
 					*out++ = sep;
-					write_count = std::min(group_size, int{last - start});
+					write_count = std::min(group_size, int(last - start));
 				}
 				return std::move(out);
 			}
diff --git a/include/rexy/detail/format/named_args.tpp b/include/rexy/detail/format/named_args.tpp
index 356be7d..8cc38a6 100644
--- a/include/rexy/detail/format/named_args.tpp
+++ b/include/rexy/detail/format/named_args.tpp
@@ -45,7 +45,7 @@ namespace rexy::fmt::detail{
 	}
 	template<class It, class... Args>
 	constexpr std::size_t find_static_named_arg_id(It first, It last){
-		if constexpr(!sizeof...(Args)){
+		if constexpr(sizeof...(Args) == 0){
 			return invalid_arg_index;
 		}else{
 			return find_static_named_arg_id_impl<It, 0, Args...>(first, last);
diff --git a/include/rexy/detail/format/specs_handler.tpp b/include/rexy/detail/format/specs_handler.tpp
index 68e4bc6..0d27e4c 100644
--- a/include/rexy/detail/format/specs_handler.tpp
+++ b/include/rexy/detail/format/specs_handler.tpp
@@ -127,7 +127,7 @@ namespace rexy::fmt::detail{
 	template<class It>
 	constexpr void dynamic_format_specs_handler<ParseCtx>::on_dynamic_width(It first, It last){
 		parse_ctx.check_arg_id(0); //just to make sure we aren't switching indexing modes
-		specs.dyn_width.name = {first, last - first};
+		specs.dyn_width.name = {first, std::size_t(last - first)};
 		specs.width_type = dyn_type::string;
 	}
 	template<class ParseCtx>
@@ -147,7 +147,7 @@ namespace rexy::fmt::detail{
 	template<class It>
 	constexpr void dynamic_format_specs_handler<ParseCtx>::on_dynamic_precision(It first, It last){
 		parse_ctx.check_arg_id(0); //just to make sure we aren't switching indexing modes
-		specs.dyn_precision.name = {first, last - first};
+		specs.dyn_precision.name = {first, std::size_t(last - first)};
 		specs.precision_type = dyn_type::string;
 	}
 	template<class ParseCtx>
diff --git a/include/rexy/detail/format/storage.tpp b/include/rexy/detail/format/storage.tpp
index 19dc5c5..0f6594a 100644
--- a/include/rexy/detail/format/storage.tpp
+++ b/include/rexy/detail/format/storage.tpp
@@ -76,16 +76,16 @@ namespace rexy::fmt::detail{
 		constexpr auto operator()(T) -> typename basic_format_arg<Context>::handle;
 		constexpr auto operator()(std::unsigned_integral auto i){
 			if constexpr(sizeof(i) <= sizeof(unsigned int)){
-				return (unsigned int){};
+				return (unsigned int)(0);
 			}else{
-				return (unsigned long long){};
+				return (unsigned long long)(0);
 			}
 		}
 		constexpr auto operator()(std::signed_integral auto i){
 			if constexpr(sizeof(i) <= sizeof(int)){
-				return int{};
+				return int(0);
 			}else{
-				return (long long){};
+				return (long long)(0);
 			}
 		}
 		template<std::floating_point T>
diff --git a/include/rexy/string_base.hpp b/include/rexy/string_base.hpp
index fe5003b..5707525 100644
--- a/include/rexy/string_base.hpp
+++ b/include/rexy/string_base.hpp
@@ -366,7 +366,7 @@ namespace rexy{
 		using const_reverse_iterator = typename string_base<Char>::const_reverse_iterator;
 		using allocator_type = Alloc;
 
-		static constexpr size_type npos = size_type{-1};
+		static constexpr size_type npos = size_type(-1);
 
 	private:
 		REXY_CPP20_CONSTEXPR void _copy_construct_string(const_pointer data, size_type len, size_type cap)
diff --git a/include/rexy/string_base.tpp b/include/rexy/string_base.tpp
index a99a031..d9c54d6 100644
--- a/include/rexy/string_base.tpp
+++ b/include/rexy/string_base.tpp
@@ -271,7 +271,7 @@ namespace rexy{
 	template<class Char, REXY_ALLOCATOR_CONCEPT Alloc>
 	REXY_CPP20_CONSTEXPR basic_string<Char,Alloc>::basic_string(size_type cap)
 		noexcept(is_nothrow_allocator_v<Alloc>):
-		basic_string(size_type{0}, cap){}
+		basic_string(size_type(0), cap){}
 	template<class Char, REXY_ALLOCATOR_CONCEPT Alloc>
 	REXY_CPP20_CONSTEXPR basic_string<Char,Alloc>::basic_string(size_type len, size_type cap)
 		noexcept(is_nothrow_allocator_v<Alloc>)
@@ -289,7 +289,7 @@ namespace rexy{
 	template<class InputIt, class Enable>
 	REXY_CPP20_CONSTEXPR basic_string<Char,Alloc>::basic_string(InputIt start, InputIt fin)
 		noexcept(is_nothrow_allocator_v<Alloc>):
-		basic_string(nullptr, size_type{fin - start})
+		basic_string(nullptr, size_type(fin - start))
 	{
 		auto raw = this->get_pointer();
 		size_type i = 0;
@@ -547,7 +547,7 @@ namespace rexy{
 		const size_type len = last - first;
 		size_type count = 0;
 		for(auto it = first2;count < len && it != last2;++count,++it);
-		return _replace_impl(size_type{first - this->begin()}, len, first2, count);
+		return _replace_impl(size_type(first - this->begin()), len, first2, count);
 	}
 	template<class Char, REXY_ALLOCATOR_CONCEPT Alloc>
 	constexpr auto basic_string<Char,Alloc>::replace(size_type pos, size_type count, const_pointer cstr, size_type count2) -> basic_string&{
@@ -555,7 +555,7 @@ namespace rexy{
 	}
 	template<class Char, REXY_ALLOCATOR_CONCEPT Alloc>
 	constexpr auto basic_string<Char,Alloc>::replace(const_iterator first, const_iterator last, const_pointer cstr, size_type count) -> basic_string&{
-		return _replace_impl(size_type{first - this->begin()}, size_type{last - first}, cstr, count);
+		return _replace_impl(size_type(first - this->begin()), size_type(last - first), cstr, count);
 	}
 	template<class Char, REXY_ALLOCATOR_CONCEPT Alloc>
 	constexpr auto basic_string<Char,Alloc>::replace(size_type pos, size_type count, const_pointer cstr) -> basic_string&{
@@ -563,7 +563,7 @@ namespace rexy{
 	}
 	template<class Char, REXY_ALLOCATOR_CONCEPT Alloc>
 	constexpr auto basic_string<Char,Alloc>::replace(const_iterator first, const_iterator last, const_pointer cstr) -> basic_string&{
-		return _replace_impl(size_type{first - this->begin()}, size_type{last - first}, cstr, rexy::strlen(cstr));
+		return _replace_impl(size_type(first - this->begin()), size_type(last - first), cstr, rexy::strlen(cstr));
 	}
 	template<class Char, REXY_ALLOCATOR_CONCEPT Alloc>
 	constexpr auto basic_string<Char,Alloc>::replace(size_type pos, size_type count, size_type count2, value_type v) -> basic_string&{
@@ -571,11 +571,11 @@ namespace rexy{
 	}
 	template<class Char, REXY_ALLOCATOR_CONCEPT Alloc>
 	constexpr auto basic_string<Char,Alloc>::replace(const_iterator first, const_iterator last, size_type count2, value_type v) -> basic_string&{
-		return _replace_impl(size_type{first - this->begin()}, size_type{last - first}, detail::value_iterator_adapter{v}, count2);
+		return _replace_impl(size_type(first - this->begin()), size_type(last - first), detail::value_iterator_adapter{v}, count2);
 	}
 	template<class Char, REXY_ALLOCATOR_CONCEPT Alloc>
 	constexpr auto basic_string<Char,Alloc>::replace(const_iterator first, const_iterator last, std::initializer_list<value_type> list) -> basic_string&{
-		return _replace_impl(size_type{first - this->begin()}, size_type{last - first}, list.begin(), list.size());
+		return _replace_impl(size_type(first - this->begin()), size_type(last - first), list.begin(), list.size());
 	}
 	template<class Char, REXY_ALLOCATOR_CONCEPT Alloc>
 	template<class StringView>
@@ -589,7 +589,7 @@ namespace rexy{
 	constexpr auto basic_string<Char,Alloc>::replace(const_iterator first, const_iterator last, const StringView& sv) ->
 		std::enable_if_t<std::is_convertible_v<const StringView&, basic_string_view<value_type>> && !std::is_convertible_v<const StringView&,const_pointer>,basic_string&>
 	{
-		return _replace_impl(size_type{first - this->begin()}, size_type{last - first}, sv.begin(), sv.length());
+		return _replace_impl(size_type(first - this->begin()), size_type(last - first), sv.begin(), sv.length());
 	}
 	template<class Char, REXY_ALLOCATOR_CONCEPT Alloc>
 	template<class StringView>
@@ -700,10 +700,10 @@ namespace rexy{
 
 		if(insert_count + len <= cap){
 
-			auto* dest_ptr = this->data() + pos + insert_count;
-			const auto* src_ptr = this->data() + pos;
+			auto* dest_ptr = this->data() + len + insert_count - 1;
+			const auto* src_ptr = this->data() + pos + insert_count;
 			for(size_type i = 0;i < after_pos_count;++i){
-				*dest_ptr++ = *src_ptr++;
+				*dest_ptr-- = *src_ptr--;
 			}
 			dest_ptr = this->data() + pos;
 			for(size_type i = 0;i < insert_count;++i){
@@ -763,7 +763,7 @@ namespace rexy{
 	}
 	template<class Left, class Right>
 	template<REXY_ALLOCATOR_CONCEPT Alloc>
-	REXY_CPP20_CONSTEXPR string_cat_expr<Left,Right>::operator basic_string<value_type,Alloc>(void)
+	REXY_CPP20_CONSTEXPR string_cat_expr<Left,Right>::operator basic_string<typename string_cat_expr<Left,Right>::value_type,Alloc>(void)
 		noexcept(std::is_nothrow_constructible<basic_string<value_type,Alloc>, typename basic_string<value_type,Alloc>::size_type>::value &&
 		         std::is_nothrow_invocable<detail::string_appender<basic_string<value_type,Alloc>>,decltype(*this)>::value)
 	{
diff --git a/include/rexy/string_view.hpp b/include/rexy/string_view.hpp
index 812e0f7..2f15f4b 100644
--- a/include/rexy/string_view.hpp
+++ b/include/rexy/string_view.hpp
@@ -46,7 +46,7 @@ namespace rexy{
 		using reverse_iterator = std::reverse_iterator<iterator>;
 		using const_reverse_iterator = std::reverse_iterator<const_iterator>;
 
-		static constexpr size_type npos = size_type{-1};
+		static constexpr size_type npos = size_type(-1);
 
 	private:
 		const_pointer m_data = nullptr;
diff --git a/src/filerd.cpp b/src/filerd.cpp
index 8ea30aa..82834df 100644
--- a/src/filerd.cpp
+++ b/src/filerd.cpp
@@ -46,14 +46,14 @@ namespace rexy{
 		tmp = ftell(m_fp);
 		fseek(m_fp, 0, SEEK_END);
 		ret = ftell(m_fp);
-		fseek(m_fp, tmp, SEEK_SET);
+		fseek(m_fp, long(tmp), SEEK_SET);
 		return ret;
 	}
 	std::size_t filerd::position(void)const noexcept{
 		return ftell(m_fp);
 	}
 	void filerd::rewind(std::size_t pos)noexcept{
-		fseek(m_fp, pos, SEEK_SET);
+		fseek(m_fp, long(pos), SEEK_SET);
 	}
 
 	filerd::operator FILE*(void)noexcept{
diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index 9af46fa..0ee0803 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -2,7 +2,14 @@ cmake_minimum_required(VERSION 3.0.2)
 project(rexylib_tests)
 set(INCLUDE_PATH ${CMAKE_CURRENT_SOURCE_DIR}/../include)
 include_directories("${INCLUDE_PATH}")
-add_compile_options(-Wall -Wextra -pedantic -std=c++20 -Wno-free-nonheap-object)
+
+set(CMAKE_CXX_STANDARD 20)
+
+if(MSVC)
+	add_compile_options("/Zc:__cplusplus" "/Wall")
+else()
+	add_compile_options("-Wall" "-Wextra" "-pedantic")
+endif()
 link_libraries(rexy)
 
 if(ENABLE_PROFILING)
diff --git a/tests/format.cpp b/tests/format.cpp
index 9bd129f..c518119 100644
--- a/tests/format.cpp
+++ b/tests/format.cpp
@@ -22,9 +22,9 @@ void test_fail(void){
 
 #define PERFORM_TEST(desired, formt, ...) \
 do{ \
-	rexy::string str = rexy::format((formt) __VA_OPT__(,) __VA_ARGS__); \
-	if(str != (desired)){ \
-		test_fail(str, desired); \
+	rexy::string str = rexy::format( (formt), __VA_ARGS__); \
+	if(str != (desired) ){ \
+		test_fail( (str), (desired) ); \
 	} \
 }while(0)
 
@@ -58,12 +58,6 @@ void do_brace_escapes(void){
 
 
 void do_empty_format(void){
-do{
-	rexy::string str = rexy::format("{}", 0);
-	if(str != "0"_sv){
-		test_fail(str.c_str(), "0"_sv);
-	}
-}while(0);
 	PERFORM_TEST("0"_sv, "{}", 0);
 	PERFORM_TEST("0"_sv, "{}", 0ul);
 	PERFORM_TEST("0"_sv, "{}", short{0});