diff --git a/include/spdlog/common.h b/include/spdlog/common.h
index 3edda553..1e446555 100644
--- a/include/spdlog/common.h
+++ b/include/spdlog/common.h
@@ -5,7 +5,6 @@
 
 #pragma once
 
-
 #include <string>
 #include <initializer_list>
 #include <chrono>
@@ -19,7 +18,6 @@
 
 #include <spdlog/details/null_mutex.h>
 
-
 //visual studio upto 2013 does not support noexcept nor constexpr
 #if defined(_MSC_VER) && (_MSC_VER < 1900)
 #define SPDLOG_NOEXCEPT throw()
@@ -30,7 +28,6 @@
 #endif
 
 
-
 namespace spdlog
 {
 
@@ -41,7 +38,6 @@ namespace sinks
 class sink;
 }
 
-// Common types across the lib
 using log_clock = std::chrono::system_clock;
 using sink_ptr = std::shared_ptr < sinks::sink >;
 using sinks_init_list = std::initializer_list < sink_ptr >;
@@ -115,21 +111,10 @@ private:
 // wchar support for windows file names (SPDLOG_WCHAR_FILENAMES must be defined)
 //
 #if defined(_WIN32) && defined(SPDLOG_WCHAR_FILENAMES)
-#define SPDLOG_FILENAME_T(s) L ## s
 using filename_t = std::wstring;
-inline std::string filename_to_str(const filename_t& filename)
-{
-    std::wstring_convert<std::codecvt_utf8<wchar_t>, wchar_t> c;
-    return c.to_bytes(filename);
-}
 #else
-#define SPDLOG_FILENAME_T(s) s
 using filename_t = std::string;
-
-inline std::string filename_to_str(const filename_t& filename)
-{
-    return filename;
-}
 #endif
 
+
 } //spdlog
diff --git a/include/spdlog/details/file_helper.h b/include/spdlog/details/file_helper.h
index 024a21b5..524c3b71 100644
--- a/include/spdlog/details/file_helper.h
+++ b/include/spdlog/details/file_helper.h
@@ -25,6 +25,7 @@ namespace details
 
 class file_helper
 {
+	
 public:
     const int open_tries = 5;
     const int open_interval = 10;
@@ -57,7 +58,7 @@ public:
             std::this_thread::sleep_for(std::chrono::milliseconds(open_interval));
         }
 
-        throw spdlog_ex("Failed opening file " + filename_to_str(_filename) + " for writing");
+        throw spdlog_ex("Failed opening file " + os::filename_to_str(_filename) + " for writing");
     }
 
     void reopen(bool truncate)
@@ -88,34 +89,30 @@ public:
         size_t msg_size = msg.formatted.size();
         auto data = msg.formatted.data();
         if (std::fwrite(data, 1, msg_size, _fd) != msg_size)
-            throw spdlog_ex("Failed writing to file " + filename_to_str(_filename));
+            throw spdlog_ex("Failed writing to file " + os::filename_to_str(_filename));
 
         if (_force_flush)
             std::fflush(_fd);
-
     }
 
     long size()
     {
         if (!_fd)
-            throw spdlog_ex("Cannot use size() on closed file " + filename_to_str(_filename));
+            throw spdlog_ex("Cannot use size() on closed file " + os::filename_to_str(_filename));
 
         auto pos = ftell(_fd);
         if (fseek(_fd, 0, SEEK_END) != 0)
-            throw spdlog_ex("fseek failed on file " + filename_to_str(_filename));
+            throw spdlog_ex("fseek failed on file " + os::filename_to_str(_filename));
 
         auto file_size = ftell(_fd);
 
         if(fseek(_fd, pos, SEEK_SET) !=0)
-            throw spdlog_ex("fseek failed on file " + filename_to_str(_filename));
+            throw spdlog_ex("fseek failed on file " + os::filename_to_str(_filename));
 
         if (file_size == -1)
-            throw spdlog_ex("ftell failed on file " + filename_to_str(_filename));
-
+            throw spdlog_ex("ftell failed on file " + os::filename_to_str(_filename));
 
         return file_size;
-
-
     }
 
     const filename_t& filename() const
@@ -129,14 +126,10 @@ public:
         return os::file_exists(name);
     }
 
-
-
 private:
     FILE* _fd;
-    filename_t _filename;
+	filename_t _filename;
     bool _force_flush;
-
-
 };
 }
 }
diff --git a/include/spdlog/details/os.h b/include/spdlog/details/os.h
index f230142e..8ebfcafc 100644
--- a/include/spdlog/details/os.h
+++ b/include/spdlog/details/os.h
@@ -112,7 +112,7 @@ inline bool operator!=(const std::tm& tm1, const std::tm& tm2)
     return !(tm1 == tm2);
 }
 
-// eol at end of each log line
+// eol definition
 #if !defined (SPDLOG_EOL)
 #ifdef _WIN32
 #define SPDLOG_EOL "\r\n"
@@ -125,6 +125,7 @@ SPDLOG_CONSTEXPR static const char* eol = SPDLOG_EOL;
 SPDLOG_CONSTEXPR static int eol_size = sizeof(SPDLOG_EOL) - 1;
 
 
+
 //fopen_s on non windows for writing
 inline int fopen_s(FILE** fp, const filename_t& filename, const filename_t& mode)
 {
@@ -228,6 +229,23 @@ inline size_t thread_id()
 
 }
 
+
+// wchar support for windows file names (SPDLOG_WCHAR_FILENAMES must be defined)
+#if defined(_WIN32) && defined(SPDLOG_WCHAR_FILENAMES)
+#define SPDLOG_FILENAME_T(s) L ## s
+inline std::string filename_to_str(const filename_t& filename)
+{
+	std::wstring_convert<std::codecvt_utf8<wchar_t>, wchar_t> c;
+	return c.to_bytes(filename);
+}
+#else
+#define SPDLOG_FILENAME_T(s) s
+inline std::string filename_to_str(const filename_t& filename)
+{
+	return filename;
+}
+#endif
+
 } //os
 } //details
 } //spdlog
diff --git a/include/spdlog/sinks/file_sinks.h b/include/spdlog/sinks/file_sinks.h
index e6fe44b6..ba3b0c5a 100644
--- a/include/spdlog/sinks/file_sinks.h
+++ b/include/spdlog/sinks/file_sinks.h
@@ -20,7 +20,7 @@
 namespace spdlog
 {
 namespace sinks
-{
+{	
 /*
 * Trivial file sink with single file as target
 */
@@ -108,6 +108,7 @@ private:
 
     void _rotate()
     {
+		using details::os::filename_to_str;
         _file_helper.close();
         for (auto i = _max_files; i > 0; --i)
         {
diff --git a/include/spdlog/spdlog.h b/include/spdlog/spdlog.h
index 2dc02090..5790afd2 100644
--- a/include/spdlog/spdlog.h
+++ b/include/spdlog/spdlog.h
@@ -19,6 +19,7 @@
 
 namespace spdlog
 {
+	
 // Return an existing logger or nullptr if a logger with such name doesn't exist.
 // Examples:
 //