diff --git a/UnitTests/UnitTests.vcxproj b/UnitTests/UnitTests.vcxproj
index 2f6f6bcd6..dc1f70e7a 100644
--- a/UnitTests/UnitTests.vcxproj
+++ b/UnitTests/UnitTests.vcxproj
@@ -123,6 +123,7 @@
     </ClCompile>
     <ClCompile Include="ring.cpp" />
     <ClCompile Include="sgml.cpp" />
+    <ClCompile Include="unicode.cpp" />
   </ItemGroup>
   <ItemGroup>
     <ClInclude Include="pch.h" />
diff --git a/UnitTests/UnitTests.vcxproj.filters b/UnitTests/UnitTests.vcxproj.filters
index 29bb1fd0d..a42e11a19 100644
--- a/UnitTests/UnitTests.vcxproj.filters
+++ b/UnitTests/UnitTests.vcxproj.filters
@@ -33,6 +33,9 @@
     <ClCompile Include="ring.cpp">
       <Filter>Source Files</Filter>
     </ClCompile>
+    <ClCompile Include="unicode.cpp">
+      <Filter>Source Files</Filter>
+    </ClCompile>
   </ItemGroup>
   <ItemGroup>
     <ClInclude Include="pch.h">
diff --git a/UnitTests/pch.h b/UnitTests/pch.h
index 30152cedc..7e2d87e1c 100644
--- a/UnitTests/pch.h
+++ b/UnitTests/pch.h
@@ -23,6 +23,7 @@
 #include <stdex/sal.hpp>
 #include <stdex/sgml.hpp>
 #include <stdex/string.hpp>
+#include <stdex/unicode.hpp>
 #include <stdex/vector_queue.hpp>
 
 #include <CppUnitTest.h>
diff --git a/UnitTests/unicode.cpp b/UnitTests/unicode.cpp
new file mode 100644
index 000000000..b740d2b07
--- /dev/null
+++ b/UnitTests/unicode.cpp
@@ -0,0 +1,48 @@
+/*
+	SPDX-License-Identifier: MIT
+	Copyright © 2023 Amebis
+*/
+
+#include "pch.h"
+
+using namespace std;
+using namespace Microsoft::VisualStudio::CppUnitTestFramework;
+
+namespace UnitTests
+{
+	TEST_CLASS(unicode)
+	{
+	public:
+		TEST_METHOD(str2wstr)
+		{
+			Assert::AreEqual(
+				L"This is a test.",
+				stdex::str2wstr("This is a test.", stdex::charset_id::utf8).c_str());
+			Assert::AreEqual(
+				L"Th\u00ed\u0161 i\u22c5 a te\u0073\u0304t. 😀😅",
+				stdex::str2wstr("Thíš i⋅ a tes̄t. 😀😅", stdex::charset_id::utf8).c_str());
+			Assert::AreEqual(
+				L"",
+				stdex::str2wstr("test", 0, stdex::charset_id::utf8).c_str());
+			Assert::AreEqual(
+				L"",
+				stdex::str2wstr(nullptr, 0, stdex::charset_id::utf8).c_str());
+		}
+
+		TEST_METHOD(wstr2str)
+		{
+			Assert::AreEqual(
+				"This is a test.",
+				stdex::wstr2str(L"This is a test.", stdex::charset_id::utf8).c_str());
+			Assert::AreEqual(
+				"Th\xc3\xad\xc5\xa1 i\xe2\x8b\x85 a tes\xcc\x84t. \xf0\x9f\x98\x80\xf0\x9f\x98\x85",
+				stdex::wstr2str(L"Thíš i⋅ a tes̄t. 😀😅", stdex::charset_id::utf8).c_str());
+			Assert::AreEqual(
+				"",
+				stdex::wstr2str(L"test", 0, stdex::charset_id::utf8).c_str());
+			Assert::AreEqual(
+				"",
+				stdex::wstr2str(nullptr, 0, stdex::charset_id::utf8).c_str());
+		}
+	};
+}
diff --git a/include/stdex/unicode.hpp b/include/stdex/unicode.hpp
index 0fcfbf6eb..289fdc336 100644
--- a/include/stdex/unicode.hpp
+++ b/include/stdex/unicode.hpp
@@ -46,6 +46,7 @@ namespace stdex
 
 		// Try to convert to stack buffer first.
 		WCHAR szStackBuffer[1024/sizeof(WCHAR)];
+#pragma warning(suppress: 6387) // Testing indicates src may be NULL when count_src is also 0. Is SAL of the lpMultiByteStr parameter wrong?
 		int cch = MultiByteToWideChar(static_cast<UINT>(charset), dwFlags, src, static_cast<int>(count_src), szStackBuffer, _countof(szStackBuffer));
 		if (cch) {
 			// Append from stack.
@@ -134,6 +135,7 @@ namespace stdex
 
 		// Try to convert to stack buffer first.
 		CHAR szStackBuffer[1024/sizeof(CHAR)];
+#pragma warning(suppress: 6387) // Testing indicates src may be NULL when count_src is also 0. Is SAL of the lpWideCharStr parameter wrong?
 		int cch = WideCharToMultiByte(static_cast<UINT>(charset), dwFlags, src, static_cast<int>(count_src), szStackBuffer, _countof(szStackBuffer), lpDefaultChar, NULL);
 		if (cch) {
 			// Copy from stack. Be careful not to include zero terminator.