diff --git a/dll/win32/kernel32/client/file/volume.c b/dll/win32/kernel32/client/file/volume.c
index e59c291b67f..90016b8e086 100644
--- a/dll/win32/kernel32/client/file/volume.c
+++ b/dll/win32/kernel32/client/file/volume.c
@@ -87,7 +87,7 @@ GetVolumeInformationA(IN LPCSTR lpRootPathName,
     /* If caller wants file system name, allocate a buffer to receive it */
     if (lpFileSystemNameBuffer != NULL)
     {
-        FileSystemNameU.MaximumLength = sizeof(WCHAR) * (nVolumeNameSize + 1);
+        FileSystemNameU.MaximumLength = sizeof(WCHAR) * (nFileSystemNameSize + 1);
         FileSystemNameU.Buffer = RtlAllocateHeap(RtlGetProcessHeap(), 0,
 	                                             FileSystemNameU.MaximumLength);
         if (FileSystemNameU.Buffer == NULL)