diff --git a/cmd.c b/cmd.c
index e5ec9cc5..04a4caf0 100644
--- a/cmd.c
+++ b/cmd.c
@@ -304,6 +304,8 @@ cmd_unpack_argv(char *buf, size_t len, int argc, char ***argv)
 
 	if (argc == 0)
 		return (0);
+	if (argc < 0 || argc > 1000)
+		return (-1);
 	*argv = xcalloc(argc, sizeof **argv);
 
 	buf[len - 1] = '\0';