diff --git a/configure.ac b/configure.ac
index eca327d..9a4aeb5 100644
--- a/configure.ac
+++ b/configure.ac
@@ -8,6 +8,6 @@
 
 AC_CONFIG_FILES([Makefile])
 
-AC_CONFIG_SUBDIRS([compiler/cpp lib/cpp lib/py])
+AC_CONFIG_SUBDIRS([compiler/cpp lib/cpp lib/py if])
 
 AC_OUTPUT