diff --git a/scripts/config.sh b/scripts/config.sh
index d764868..6519aaf 100644
--- a/scripts/config.sh
+++ b/scripts/config.sh
@@ -116,6 +116,7 @@ function register_existing() {
 	local new_id="${arguments[new_id]}"
 	local device="${arguments[device]}"
 	create_resolve_entry_device "$new_id" "$device"
+	DISK_ACTIONS+=("action=existing" "$@" ";")
 }
 
 # Named arguments:
@@ -348,7 +349,7 @@ function create_single_disk_layout() {
 	die "'create_single_disk_layout' is deprecated, please use 'create_classic_single_disk_layout' instead. It is fully option-compatible to the old version."
 }
 
-# Skip partitioning, and use existing partitions.
+# Skip partitioning, and use existing pre-formatted partitions. These must be trivially mountable.
 # Parameters:
 #   swap=<device|false>   Use the given device as swap, or no swap at all if set to false
 #   boot=<device>         Use the given device as the bios/efi partition.
diff --git a/scripts/functions.sh b/scripts/functions.sh
index 43f3583..ce9c0a1 100644
--- a/scripts/functions.sh
+++ b/scripts/functions.sh
@@ -163,6 +163,14 @@ function summary_color_args() {
 	done
 }
 
+function disk_existing() {
+	local new_id="${arguments[new_id]}"
+	if [[ ${disk_action_summarize_only-false} == "true" ]]; then
+		add_summary_entry __root__ "$new_id" "${arguments[device]}" "(no-format, existing)" ""
+	fi
+	# no-op;
+}
+
 function disk_create_gpt() {
 	local new_id="${arguments[new_id]}"
 	if [[ ${disk_action_summarize_only-false} == "true" ]]; then
@@ -563,6 +571,7 @@ function apply_disk_action() {
 	unset known_arguments
 	unset arguments; declare -A arguments; parse_arguments "$@"
 	case "${arguments[action]}" in
+		'existing')          disk_existing         ;;
 		'create_gpt')        disk_create_gpt       ;;
 		'create_partition')  disk_create_partition ;;
 		'create_raid')       disk_create_raid      ;;