diff --git a/src/proto.h b/src/proto.h
index c301857..842d891 100644
--- a/src/proto.h
+++ b/src/proto.h
@@ -178,6 +178,7 @@
 # include "normal.pro"
 # include "ops.pro"
 # include "option.pro"
+# include "optionstr.pro"
 # include "popupmnu.pro"
 # if defined(FEAT_PROFILE) || defined(FEAT_RELTIME)
 # include "profiler.pro"