diff --git a/src/proto.h b/src/proto.h
index 269d81c..e854546 100644
--- a/src/proto.h
+++ b/src/proto.h
@@ -89,6 +89,7 @@
 # endif
 # include "hardcopy.pro"
 # include "hashtab.pro"
+# include "highlight.pro"
 # include "indent.pro"
 # ifdef FEAT_INS_EXPAND
 # include "insexpand.pro"