diff --git a/usr.bin/unifdef/unifdef.1 b/usr.bin/unifdef/unifdef.1
index e6031c8d7c72..556bec102cc2 100644
--- a/usr.bin/unifdef/unifdef.1
+++ b/usr.bin/unifdef/unifdef.1
@@ -253,7 +253,7 @@ utility exits 0 if the output is an exact copy of the input,
 .Sh BUGS
 Expression evaluation is very limited.
 .Pp
-Does not work correctly if input contains null characters.
+Does not work correctly if input contains nul characters.
 .Sh HISTORY
 The
 .Nm