diff --git a/configure.ac b/configure.ac
index 9e0c3211e..fb609882c 100644
--- a/configure.ac
+++ b/configure.ac
@@ -29,7 +29,7 @@ AC_REVISION([$Revision$])
 AC_CONFIG_HEADER([src/include/ngspice/config.h])
 
 # Initialise automake stuff
-AM_INIT_AUTOMAKE([-Wall -Werror nostdinc serial-tests])
+AM_INIT_AUTOMAKE([-Wall -Werror nostdinc serial-tests subdir-objects])
 m4_ifdef([AM_SILENT_RULES], [AM_SILENT_RULES([yes])])
 
 ext_CFLAGS="${CFLAGS+yes}"