diff --git a/hw/block/swim.c b/hw/block/swim.c
index 8f12478..74f56e8 100644
--- a/hw/block/swim.c
+++ b/hw/block/swim.c
@@ -189,7 +189,10 @@
         assert(ret == 0);
     }
 
-    blkconf_blocksizes(&dev->conf);
+    if (!blkconf_blocksizes(&dev->conf, errp)) {
+        return;
+    }
+
     if (dev->conf.logical_block_size != 512 ||
         dev->conf.physical_block_size != 512)
     {