--- a/Source/troff_generator.c	2021-01-28 23:24:55.000000000 +0100
+++ b/Source/troff_generator.c	2024-02-16 16:30:54.120883223 +0100
@@ -30,7 +30,7 @@
 #include <ctype.h>
 
 #include <sys/param.h>
-#include <sys/unistd.h>
+#include <unistd.h>
 
 #include "troff_generator.h"
 #include "util.h"
@@ -560,6 +560,6 @@
  * SOURCE
  */
 {
-    fprintf( dest_doc, line_number_string );
+    fprintf( dest_doc, "%s", line_number_string );
 }
 /******/