diff --git a/config/sql/se/Collections.sql b/config/sql/se/Collections.sql
index 84d38dec..2a6d99ff 100644
--- a/config/sql/se/Collections.sql
+++ b/config/sql/se/Collections.sql
@@ -2,7 +2,7 @@ CREATE TABLE `Collections` (
   `CollectionId` int(10) unsigned NOT NULL AUTO_INCREMENT,
   `Name` varchar(255) NOT NULL,
   `UrlName` varchar(255) NOT NULL,
-  `Type` varchar(255) NULL,
+  `Type` enum('series', 'set') NULL,
   PRIMARY KEY (`CollectionId`),
   UNIQUE KEY `idxUnique` (`UrlName`)
 ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;
diff --git a/lib/Collection.php b/lib/Collection.php
index 8c6b8a95..66e7d9ce 100644
--- a/lib/Collection.php
+++ b/lib/Collection.php
@@ -10,7 +10,7 @@ class Collection{
 	public int $CollectionId;
 	public string $Name;
 	public string $UrlName;
-	public ?string $Type = null;
+	public ?CollectionType $Type = null;
 	protected ?string $_Url = null;
 
 	protected function GetUrl(): ?string{
@@ -59,7 +59,7 @@ class Collection{
 			$error->Add(new Exceptions\StringTooLongException('Collection name: '. $this->Name));
 		}
 
-		if($this->Type !== null && ($this->Type != 'series' && $this->Type != 'set')){
+		if($this->Type !== null && ($this->Type != CollectionType::Series && $this->Type != CollectionType::Set)){
 			$error->Add(new Exceptions\InvalidCollectionTypeException($this->Type));
 		}
 
diff --git a/lib/CollectionType.php b/lib/CollectionType.php
new file mode 100644
index 00000000..f3de077e
--- /dev/null
+++ b/lib/CollectionType.php
@@ -0,0 +1,6 @@
+<?
+enum CollectionType: string{
+	case Series = 'series';
+	case Set = 'set';
+	case Unknown = 'unknown';
+}
diff --git a/lib/Ebook.php b/lib/Ebook.php
index 1de2a8cc..25666390 100644
--- a/lib/Ebook.php
+++ b/lib/Ebook.php
@@ -762,7 +762,7 @@ class Ebook{
 				$cm->SequenceNumber = (int)$s;
 			}
 			foreach($xml->xpath('/package/metadata/meta[@refines="#' . $id . '"][@property="collection-type"]') ?: [] as $s){
-				$cm->Collection->Type = (string)$s;
+				$cm->Collection->Type = CollectionType::tryFrom((string)$s) ?? CollectionType::Unknown;
 			}
 			$collectionMemberships[] = $cm;
 		}