diff --git a/build-qemu b/build-qemu
index 054a052..de70cb6 100755
--- a/build-qemu
+++ b/build-qemu
@@ -9,7 +9,13 @@ class Main(common.BuildCliFunction):
     def __init__(self):
         super().__init__()
         self._add_argument('--configure')
-        self.add_argument('--extra-config-args')
+        self.add_argument(
+            '--extra-config-args',
+            default='',
+            help='''\
+Extra arguments to pass to configure
+'''
+        )
         self._add_argument('extra_make_args')
 
     def build(self):