diff --git a/src/file_win.cpp b/src/file_win.cpp
index f5012a3b2..50fa7da10 100644
--- a/src/file_win.cpp
+++ b/src/file_win.cpp
@@ -66,7 +66,7 @@ namespace
 			std::string ret;
 			ret.resize(size);
 			size = wcstombs(&ret[0], ws.c_str(), size + 1);
-			if (ret == wchar_t(-1)) return s;
+			if (size == wchar_t(-1)) return s;
 			ret.resize(size);
 			return ret;
 		}