diff --git a/doc/makedefs.6 b/doc/makedefs.6
index 55ef956a7..b0176470d 100644
--- a/doc/makedefs.6
+++ b/doc/makedefs.6
@@ -71,17 +71,17 @@ Upper and lower case are both accepted for the short commands.
 .TP
 .B \-o
 Generate
-.I onames.h.
+.IR onames.h .
 .br
 .TP
 .B \-d
 Generate
-.I data.base.
+.IR data.base .
 .br
 .TP
 .B \-e
 Generate
-.I dungeon.pdf.
+.IR dungeon.pdf .
 The input file
 .I dungeon.def
 is passed through the