diff --git a/src/digraph.c b/src/digraph.c
index 5b56095..8a3bf12 100644
--- a/src/digraph.c
+++ b/src/digraph.c
@@ -2180,7 +2180,7 @@
 			       wrong, in which case we messed up ScreenLines */
 }
 
-struct dg_header_entry {
+static struct dg_header_entry {
     int	    dg_start;
     char    *dg_header;
 } header_table[] = {