diff --git a/components/storage_monitor/storage_monitor_linux.cc b/components/storage_monitor/storage_monitor_linux.cc
index 75f5629589314..ed7a85884ea52 100644
--- a/components/storage_monitor/storage_monitor_linux.cc
+++ b/components/storage_monitor/storage_monitor_linux.cc
@@ -420,8 +420,10 @@ void StorageMonitorLinux::HandleDeviceMountedMultipleTimes(
   CHECK(priority != mount_priority_map_.end());
   const base::FilePath& other_mount_point = priority->second.begin()->first;
   priority->second[mount_point] = false;
-  mount_info_map_[mount_point] =
-      mount_info_map_.find(other_mount_point)->second;
+  auto other_info = mount_info_map_.find(other_mount_point);
+  // crbug.com/####: EjectDevice() can desync mount_priority_map_.
+  CHECK(other_info != mount_info_map_.end());
+  mount_info_map_[mount_point] = other_info->second;
 }
 
 void StorageMonitorLinux::AddNewMount(