diff --git a/usr.bin/rpcgen/rpc_main.c b/usr.bin/rpcgen/rpc_main.c
index 34755349d214..698017c969f2 100644
--- a/usr.bin/rpcgen/rpc_main.c
+++ b/usr.bin/rpcgen/rpc_main.c
@@ -93,18 +93,12 @@ static int allnc = nitems(allnv);
  */
 static void addarg(const char *);	/* add another argument to the list */
 static void insarg(int, const char *);	/* insert arg at specified location */
-static void clear_args(void);		/* clear argument list */
 static void checkfiles(const char *, const char *);
 					/* check if out file already exists */
 
-
-
-#define	ARGLISTLEN	20
-#define	FIXEDARGS	0
-
-static char *arglist[ARGLISTLEN];
-static int argcount = FIXEDARGS;
-
+static char **arglist;
+static int argcount = 0;
+static int argmax = 0;
 
 int nonfatalerrors;	/* errors */
 int inetdflag = 0;	/* Support for inetd is disabled by default, use -I */
@@ -141,7 +135,6 @@ main(int argc, const char *argv[])
 	struct commandline cmd;
 
 	(void) memset((char *)&cmd, 0, sizeof (struct commandline));
-	clear_args();
 	if (!parseargs(argc, argv, &cmd))
 		usage();
 	/*
@@ -273,16 +266,6 @@ add_warning(void)
 	f_print(fout, " */\n\n");
 }
 
-/* clear list of arguments */
-static void
-clear_args(void)
-{
-	int i;
-	for (i = FIXEDARGS; i < ARGLISTLEN; i++)
-		arglist[i] = NULL;
-	argcount = FIXEDARGS;
-}
-
 /* prepend C-preprocessor and flags before arguments */
 static void
 prepend_cpp(void)
@@ -924,22 +907,41 @@ do_registers(int argc, const char *argv[])
 	return (1);
 }
 
+/*
+ * Extend the argument list
+ */
+static void
+moreargs(void)
+{
+	char **newarglist;
+
+	argmax = argmax == 0 ? 32 : argmax << 1;
+	if (argmax > INT_MAX / 4) {
+		warnx("refusing to allocate too many arguments");
+		crash();
+	}
+	newarglist = realloc(arglist, argmax * sizeof(*arglist));
+	if (newarglist == NULL) {
+		warnx("unable to allocate arglist");
+		crash();
+	}
+	free(arglist);
+	arglist = newarglist;
+}
+
 /*
  * Add another argument to the arg list
  */
 static void
 addarg(const char *cp)
 {
-	if (argcount >= ARGLISTLEN) {
-		warnx("too many defines");
-		crash();
-		/*NOTREACHED*/
-	}
+	if (argcount >= argmax)
+		moreargs();
+
 	if (cp != NULL)
 		arglist[argcount++] = xstrdup(cp);
 	else
 		arglist[argcount++] = NULL;
-
 }
 
 /*
@@ -950,11 +952,8 @@ insarg(int place, const char *cp)
 {
 	int i;
 
-	if (argcount >= ARGLISTLEN) {
-		warnx("too many defines");
-		crash();
-		/*NOTREACHED*/
-	}
+	if (argcount >= argmax)
+		moreargs();
 
 	/* Move up existing arguments */
 	for (i = argcount - 1; i >= place; i--)