diff --git a/src/os/bluestore/BlueStore.cc b/src/os/bluestore/BlueStore.cc
index 90c78c71c4f..b31462d8975 100644
--- a/src/os/bluestore/BlueStore.cc
+++ b/src/os/bluestore/BlueStore.cc
@@ -9267,6 +9267,7 @@ int BlueStore::expand_devices(ostream& out)
                 << std::dec << "(" << byte_u_t(size) << ")"
                 << std::endl;
           }
+          ceph_assert(mounted);
           bluefs->expand_device(devid, size, old_size);
         }
       }