diff --git a/src/proto.h b/src/proto.h
index e4153eb..d7e6316 100644
--- a/src/proto.h
+++ b/src/proto.h
@@ -87,6 +87,7 @@
 # endif
 # include "hardcopy.pro"
 # include "hashtab.pro"
+# include "indent.pro"
 # include "json.pro"
 # include "list.pro"
 # include "blob.pro"