diff --git a/hw/usb/ccid-card-emulated.c b/hw/usb/ccid-card-emulated.c
index 094284d664..deb6d4703b 100644
--- a/hw/usb/ccid-card-emulated.c
+++ b/hw/usb/ccid-card-emulated.c
@@ -503,9 +503,15 @@ static int emulated_initfn(CCIDCardState *base)
     if (init_pipe_signaling(card) < 0) {
         return -1;
     }
-    card->backend = parse_enumeration(card->backend_str, backend_enum_table, 0);
+
+    card->backend = 0;
+    if (card->backend_str) {
+        card->backend = parse_enumeration(card->backend_str,
+                                          backend_enum_table, 0);
+    }
+
     if (card->backend == 0) {
-        printf("unknown backend, must be one of:\n");
+        printf("backend must be one of:\n");
         for (ptable = backend_enum_table; ptable->name != NULL; ++ptable) {
             printf("%s\n", ptable->name);
         }