diff -ru unproto5/Makefile unproto-1.7/Makefile
--- unproto5/Makefile	2019-03-29 18:16:34.000000000 +0100
+++ unproto-1.7/Makefile	2019-03-29 19:12:15.000000000 +0100
@@ -67,23 +68,35 @@
 # length argument lists, edit the stdarg.h file provided with this
 # package so that it contains the proper definitions for your machine.
 
+# Place the directive that your compiler uses for line control here.
+# Some pre-ANSI compiler use "#line", but most use simply "#".
+#
+LINE = -DLINE=\"\#line\"
+
+# If your compiler's provides an stdarg.h file that is incompatible
+# with unproto's one, define STDARG here:
+#
+STDARG = -DSTDARG
+
 ## END CONFIGURATION STUFF
 
 SHELL	= /bin/sh
diff -ru unproto5/tok_io.c unproto-1.7/tok_io.c
--- unproto5/tok_io.c	2019-03-29 18:16:34.000000000 +0100
+++ unproto-1.7/tok_io.c	2019-03-29 09:18:53.000000000 +0100
@@ -215,7 +216,8 @@
 	     * all line control tokens to stdout.
 	     */
 
-	    put_str("# ");
+	    put_str(LINE);
+	    put_ch(' ');
 	    line = atoi(t->vstr->str);		/* extract line number */
 	    tok_flush(t);
 	    while ((t = tok_get()) && t->tokno == TOK_WSPACE)
@@ -281,7 +284,7 @@
 
 /* tok_get - get next token */
 
-static int last_tokno = '\n';
+static int new_line = 1;
 
 struct token *tok_get()
 {
@@ -326,7 +329,7 @@
 	    COLLECT(t->vstr, c, ISDOT(c));
 	    t->tokno = TOK_OTHER;
 	    break;
-	} else if (c == '#' && last_tokno == '\n') {
+	} else if (c == '#' && new_line) {
 	    do_control();
 	    continue;
 	} else {
@@ -358,7 +361,12 @@
 	    break;
 	}
     }
-    last_tokno = t->tokno;
+    if (t->tokno == '\n')
+	new_line = 1;
+    else if (t->tokno == TOK_WSPACE)
+	;
+    else
+	new_line = 0;
     t->end_line = in_line;
     return (t);
 }
@@ -552,7 +560,7 @@
     if (last_ch != '\n')			/* terminate open line */
 	put_nl();
     if (path != out_path || line < out_line) {	/* file switch or back jump */
-	printf("# %d %s\n", out_line = line, out_path = path);
+	printf("%s %d %s\n", LINE, out_line = line, out_path = path);
 	last_ch = '\n';
     } else {					/* forward jump */
 	while (line > out_line)
diff -ru unproto5/unproto.c unproto-1.7/unproto.c
--- unproto5/unproto.c	2019-03-29 18:16:34.000000000 +0100
+++ unproto-1.7/unproto.c	2019-03-29 18:19:19.000000000 +0100
@@ -147,7 +147,11 @@
 /* Application-specific stuff */
 
 #include "vstring.h"
-#include "stdarg.h"
+#ifdef STDARG
+ #include <stdarg.h>
+#else
+ #include "stdarg.h"
+#endif
 #include "token.h"
 #include "error.h"
 #include "symbol.h"