diff --git a/src/Makefile.am b/src/Makefile.am
index b62e7d0..912a98c 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -1,5 +1,6 @@
 # Process this file with automake to produce Makefile.in
 
+NULL =
 SUBDIRS =
 DIST_SUBDIRS =
 BUILT_SOURCES =