diff --git a/usr.sbin/config/config.y b/usr.sbin/config/config.y
index 344a7774c011..714dbe1853d8 100644
--- a/usr.sbin/config/config.y
+++ b/usr.sbin/config/config.y
@@ -191,6 +191,9 @@ Config_spec:
 		} |
 	HINTS ID
 	      = {
+		      if (hints != NULL)
+			      errx(1, "More than one 'hints' line at %s:%d",
+				  yyfile, yyline);
 		      hints = $2;
 		      hintmode = 1;
 	        }