diff --git a/programs/x509/load_roots.c b/programs/x509/load_roots.c
index 69357ff..040ef29 100644
--- a/programs/x509/load_roots.c
+++ b/programs/x509/load_roots.c
@@ -172,7 +172,11 @@
             opt.iterations = atoi( q ) != 0;
         }
         else
+        {
             mbedtls_printf( "Unknown option: %s\n", p );
+            mbedtls_printf( USAGE );
+            goto exit;
+        }
     }
 
     opt.filenames = (const char**) argv + i;