diff --git a/include/spdlog/sinks/win_eventlog_sink.h b/include/spdlog/sinks/win_eventlog_sink.h
index 384fa9eb..7b50b7b5 100644
--- a/include/spdlog/sinks/win_eventlog_sink.h
+++ b/include/spdlog/sinks/win_eventlog_sink.h
@@ -55,20 +55,34 @@ struct win32_error : public spdlog_ex
     {
         std::string system_message;
 
+        auto fFormatResult = [&system_message](bool format_message_succeeded, void* format_message_result)
+        {
+            if (format_message_succeeded && format_message_result)
+            {
+                system_message = fmt::format(" ({})", format_message_result);
+            }
+
+            if (format_message_result)
+            {
+                LocalFree((HLOCAL)format_message_result);
+            }
+        };
+
+#ifdef SPDLOG_WCHAR_TO_UTF8_SUPPORT
+        LPWSTR format_message_result{};
+        auto format_message_succeeded =
+            ::FormatMessageW(FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS, nullptr,
+                error_code, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), (LPWSTR)&format_message_result, 0, nullptr);
+
+        fFormatResult(format_message_succeeded, format_message_result);
+#else
         LPSTR format_message_result{};
         auto format_message_succeeded =
-            ::FormatMessage(FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS, nullptr,
+            ::FormatMessageA(FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS, nullptr,
                 error_code, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), (LPSTR)&format_message_result, 0, nullptr);
 
-        if (format_message_succeeded && format_message_result)
-        {
-            system_message = fmt::format(" ({})", format_message_result);
-        }
-
-        if (format_message_result)
-        {
-            LocalFree((HLOCAL)format_message_result);
-        }
+        fFormatResult(format_message_succeeded, format_message_result);
+#endif
 
         return fmt::format("{}: {}{}", user_message, error_code, system_message);
     }
@@ -203,7 +217,7 @@ private:
     {
         if (!hEventLog_)
         {
-            hEventLog_ = ::RegisterEventSource(nullptr, source_.c_str());
+            hEventLog_ = ::RegisterEventSourceA(nullptr, source_.c_str());
             if (!hEventLog_ || hEventLog_ == (HANDLE)ERROR_ACCESS_DENIED)
             {
                 SPDLOG_THROW(internal::win32_error("RegisterEventSource"));
@@ -218,13 +232,22 @@ protected:
     {
         using namespace internal;
 
+        bool succeeded;
         memory_buf_t formatted;
         base_sink<Mutex>::formatter_->format(msg, formatted);
         formatted.push_back('\0');
-        LPCSTR lp_str = static_cast<LPCSTR>(formatted.data());
 
-        auto succeeded = ::ReportEvent(event_log_handle(), eventlog::get_event_type(msg), eventlog::get_event_category(msg), event_id_,
-            current_user_sid_.as_sid(), 1, 0, &lp_str, nullptr);
+#ifdef SPDLOG_WCHAR_TO_UTF8_SUPPORT
+            LPCWSTR lp_str = reinterpret_cast<LPCWSTR>(formatted.data());
+
+            succeeded = ::ReportEventW(event_log_handle(), eventlog::get_event_type(msg), eventlog::get_event_category(msg), event_id_,
+                current_user_sid_.as_sid(), 1, 0, &lp_str, nullptr);
+#else
+            LPCSTR lp_str = reinterpret_cast<LPCSTR>(formatted.data());
+
+            succeeded = ::ReportEventA(event_log_handle(), eventlog::get_event_type(msg), eventlog::get_event_category(msg), event_id_,
+                current_user_sid_.as_sid(), 1, 0, &lp_str, nullptr);
+#endif
 
         if (!succeeded)
         {