diff --git a/programs/x509/cert_write.c b/programs/x509/cert_write.c
index ad3dacd..ea20144 100644
--- a/programs/x509/cert_write.c
+++ b/programs/x509/cert_write.c
@@ -241,7 +241,7 @@
     mbedtls_x509_crt_init(&issuer_crt);
     memset(buf, 0, 1024);
 
-    if (argc == 0) {
+    if (argc < 2) {
 usage:
         mbedtls_printf(USAGE);
         goto exit;