diff --git a/Command/WebApp.hs b/Command/WebApp.hs
index 30bd2ffab9..6b9b8f783c 100644
--- a/Command/WebApp.hs
+++ b/Command/WebApp.hs
@@ -5,6 +5,8 @@
  - Licensed under the GNU GPL version 3 or higher.
  -}
 
+{-# LANGUAGE CPP #-}
+
 module Command.WebApp where
 
 import Common.Annex