diff --git a/src/structs.h b/src/structs.h
index aa59bff..ae1c12e 100644
--- a/src/structs.h
+++ b/src/structs.h
@@ -737,6 +737,7 @@
 typedef struct signgroup_S
 {
     short_u	refcount;		// number of signs in this group
+    int		next_sign_id;		// next sign id for this group
     char_u	sg_name[1];		// sign group name
 } signgroup_T;