diff --git a/tools/build.py b/tools/build.py
index 7e9bb2e5d9..275d89cdf9 100644
--- a/tools/build.py
+++ b/tools/build.py
@@ -46,7 +46,7 @@ if __name__ == '__main__':
     parser.add_argument("--source", dest="source_dir", type=argparse_filestring_type,
                         default=None, help="The source (input) directory", action="append")
 
-    parser.add_argument("--build", dest="build_dir", type=argparse_filestring_type,
+    parser.add_argument("--build", dest="build_dir",
                       default=None, help="The build (output) directory")
 
     parser.add_argument("--no-archive", dest="no_archive", action="store_true",