diff --git a/block/blkdebug.c b/block/blkdebug.c
index d61ece86a9eb65e8e2506e99b20b5a669e2ce818..c9041ec3d245262f82e92e39685f549ee7d9d796 100644
--- a/block/blkdebug.c
+++ b/block/blkdebug.c
@@ -240,6 +240,11 @@ static int read_config(BDRVBlkdebugState *s, const char *filename)
     int ret;
     struct add_rule_data d;
 
+    /* Allow usage without config file */
+    if (!*filename) {
+        return 0;
+    }
+
     f = fopen(filename, "r");
     if (f == NULL) {
         return -errno;