diff --git a/tools/config/__init__.py b/tools/config/__init__.py
index e963fd1b38..cbc1addb5c 100644
--- a/tools/config/__init__.py
+++ b/tools/config/__init__.py
@@ -684,7 +684,7 @@ class Config(object):
         size = self._header_size(header_format)
         region = Region("header", start, size, False, None)
         start += size
-        start = ((start + 7) // 8) * 8
+        start = ((start + (2**7 - 1)) // (2**7)) * (2**7)
         return (start, region)
 
     @staticmethod