diff --git a/src/driver/ntux_driver_ctx.c b/src/driver/ntux_driver_ctx.c
index e2440b5..47718ce 100644
--- a/src/driver/ntux_driver_ctx.c
+++ b/src/driver/ntux_driver_ctx.c
@@ -259,6 +259,7 @@ int ntux_get_driver_ctx(
 	size_t				nunits;
 	const char *			program;
 	char **				parg;
+	char **				pargcap;
 	char **				cmdargv;
 	char *				cmdmark;
 	char **				execargv;
@@ -304,18 +305,19 @@ int ntux_get_driver_ctx(
 	/* initial argv scan: ... --cmd=xxx ... */
 	argv_scan(argv,optv,&ctx,0);
 
-	/* invalid ntux arguments? */
-	if (ctx.erridx && !ctx.unitidx) {
-		if (flags & NTUX_DRIVER_VERBOSITY_ERRORS)
-			argv_get(
-				argv,optv,
-				ARGV_VERBOSITY_ERRORS,
-				fdctx->fderr);
-		return -1;
-	}
+	/* position of last base ntux argument */
+	if (ctx.erridx && ctx.unitidx)
+		pargcap = &argv[ctx.unitidx];
+
+	else if (ctx.erridx)
+		pargcap = &argv[ctx.erridx];
+
+	else
+		for (pargcap=argv; *pargcap; pargcap++)
+			(void)0;
 
 	/* scan for --cmd */
-	for (parg=argv, cmdargv=0; (parg<&argv[ctx.unitidx]) && !cmdargv; parg++) {
+	for (parg=argv, cmdargv=0; (parg<pargcap) && !cmdargv; parg++) {
 		if (!strcmp(*parg,"--cmd") && parg[1]) {
 				cmdargv = &parg[2];
 				cmdmark = parg[2];
@@ -325,6 +327,28 @@ int ntux_get_driver_ctx(
 		}
 	}
 
+	/* invalid ntux arguments? */
+	if (!ctx.erridx) {
+		(void)0;
+
+	} else if (&argv[ctx.erridx] >= cmdargv) {
+		(void)0;
+
+	} else if ((cctx.cmd == NTUX_CMD_SPAWN) && (ctx.erridx > ctx.unitidx)) {
+		(void)0;
+
+	} else if ((cctx.cmd == NTUX_CMD_STRACE) && (ctx.erridx > ctx.unitidx)) {
+		(void)0;
+
+	} else {
+		if (flags & NTUX_DRIVER_VERBOSITY_ERRORS)
+			argv_get(
+				argv,optv,
+				ARGV_VERBOSITY_ERRORS,
+				fdctx->fderr);
+		return -1;
+	}
+
 	/* process argv entries preceding --cmd */
 	if (cmdargv) {
 		*cmdargv = 0;