diff --git a/src/osd/modules/file/winfile.cpp b/src/osd/modules/file/winfile.cpp
index 1f85fc15645..62f5681e697 100644
--- a/src/osd/modules/file/winfile.cpp
+++ b/src/osd/modules/file/winfile.cpp
@@ -207,11 +207,8 @@ osd_file::error osd_file::open(std::string const &orig_path, UINT32 openflags, p
 		// create the path if necessary
 		if ((ERROR_PATH_NOT_FOUND == err) && (openflags & OPEN_FLAG_CREATE) && (openflags & OPEN_FLAG_CREATE_PATHS))
 		{
-			// the code below assumes these are the same
-			assert(std::string::npos == std::wstring::npos);
-
 			auto pathsep = t_path.rfind('\\');
-			if (pathsep != std::string::npos)
+			if (pathsep != decltype(t_path)::npos)
 			{
 				// create the path up to the file
 				t_path[pathsep] = 0;
diff --git a/src/osd/strconv.cpp b/src/osd/strconv.cpp
index 3919dddbf18..49a70f52684 100644
--- a/src/osd/strconv.cpp
+++ b/src/osd/strconv.cpp
@@ -25,9 +25,9 @@ std::string &astring_from_utf8(std::string &dst, const char *s)
 	std::basic_string<WCHAR> wstring = wstring_from_utf8(s);
 
 	// convert UTF-16 to "ANSI code page" string
-	int char_count = WideCharToMultiByte(CP_ACP, 0, wstring.c_str(), wstring.size() + 1, nullptr, 0, nullptr, nullptr);
-	dst.resize(char_count - 1);
-	WideCharToMultiByte(CP_ACP, 0, wstring.c_str(), wstring.size() + 1, &dst[0], char_count - 1, nullptr, nullptr);
+	int char_count = WideCharToMultiByte(CP_ACP, 0, wstring.c_str(), wstring.size(), nullptr, 0, nullptr, nullptr);
+	dst.resize(char_count);
+	WideCharToMultiByte(CP_ACP, 0, wstring.c_str(), wstring.size(), &dst[0], char_count, nullptr, nullptr);
 
 	return dst;
 }