Index: lib/tmpdir.rb
===================================================================
--- lib/tmpdir.rb	(revision 22794)
+++ lib/tmpdir.rb	(working copy)
@@ -16,7 +16,7 @@
     max_pathlen = 260
     windir = "\0"*(max_pathlen+1)
     begin
-      getdir = Win32API.new('shell32', 'SHGetFolderPath', 'LLLLP', 'L')
+      getdir = Win32API.new('shell32', 'SHGetFolderPath', 'LLLLP', 'L', :stdcall)
       raise RuntimeError if getdir.call(0, CSIDL_LOCAL_APPDATA, 0, 0, windir) != 0
       windir.rstrip!
     rescue RuntimeError