diff --git a/contrib/notmuch-deliver/src/Makefile.am b/contrib/notmuch-deliver/src/Makefile.am
index 939dc856..fbb29ab2 100644
--- a/contrib/notmuch-deliver/src/Makefile.am
+++ b/contrib/notmuch-deliver/src/Makefile.am
@@ -1,4 +1,5 @@
 DEFS+= -DGITHEAD=\"$(GITHEAD)\"
+AM_CPPFLAGS= -I$(top_srcdir)
 AM_CFLAGS= @NOTMUCH_DELIVER_CFLAGS@ $(glib_CFLAGS)
 
 noinst_HEADERS=\