diff --git a/service/lib/y2storage/agama_proposal.rb b/service/lib/y2storage/agama_proposal.rb
index 9d68c419da..e9f42e78d1 100644
--- a/service/lib/y2storage/agama_proposal.rb
+++ b/service/lib/y2storage/agama_proposal.rb
@@ -210,9 +210,7 @@ def drives_with_empty_partition_table(devicegraph)
     #
     # @return [Array<String>] names of partitionable devices
     def disks_for_clean
-      return drives_names if config.boot_device.nil? || drives_names.include?(config.boot_device)
-
-      drives_names + [config.boot_device]
+      (drives_names + [config.boot_device]).compact.uniq
     end
 
     # Creates the planned devices on a given devicegraph