diff --git a/programs/pkey/dh_genprime.c b/programs/pkey/dh_genprime.c
index b09ef42..9037ce3 100644
--- a/programs/pkey/dh_genprime.c
+++ b/programs/pkey/dh_genprime.c
@@ -75,7 +75,7 @@
     mbedtls_ctr_drbg_init(&ctr_drbg);
     mbedtls_entropy_init(&entropy);
 
-    if (argc == 0) {
+    if (argc < 2) {
 usage:
         mbedtls_printf(USAGE);
         goto exit;