patch-ad:
--- src/compile.c.orig	Sun Jan 26 03:42:23 1997
+++ src/compile.c	Sat Feb 13 02:29:14 1999
@@ -2,6 +2,7 @@
 
 #include <fcntl.h>
 #include <sys/stat.h>
+#include <dlfcn.h>
 
 #if	!defined(MAXPATHLEN)
 #define	MAXPATHLEN	1024
@@ -25,6 +26,9 @@
 #elif	defined(USE_IRIX5)
 #include "irix5/compile.c"
 
+#elif	defined(USE_FREEBSD)
+#include "freebsd/compile.c"
+
 #elif	defined(USE_LINUXAOUT)
 #include "linuxaout/compile.c"
 
@@ -263,7 +267,6 @@
 			int kflag; char **Cflags, *o_file, *c_file;
 {
     extern int	fork			_PARAMS((void));
-    extern int	execvp			_PARAMS((const char *, char **));
 
     struct stat	stat_c, stat_o;
 
@@ -483,6 +486,10 @@
 {
 
 #define	RECIEVE		"[Rr][Ee][Cc][IiEe][Ee][Vv]"
+
+#if	defined(USE_FREEBSD)
+#include	<unistd.h>
+#endif
 
 #if	defined(SVR4) || defined(__svr4__)
 #include <regexpr.h>