diff --git a/libaegisub/windows/fs.cpp b/libaegisub/windows/fs.cpp
index f626407e2..fbd28c7fe 100644
--- a/libaegisub/windows/fs.cpp
+++ b/libaegisub/windows/fs.cpp
@@ -35,7 +35,11 @@ namespace bfs = boost::filesystem;
 
 namespace agi { namespace fs {
 std::string ShortName(path const& p) {
-	std::wstring out(MAX_PATH + 1, 0);
+	DWORD length = GetShortPathName(p.c_str(), NULL, 0);
+	if (!length)
+		return p.string();
+
+	std::wstring out(length, 0);
 	DWORD len = GetShortPathName(p.c_str(), &out[0], out.size());
 	if (!len)
 		return p.string();