diff --git a/shared/lib/Json/JsonSerializableCollection.php b/shared/lib/Json/JsonSerializableCollection.php
index 4335398..8c75df3 100644
--- a/shared/lib/Json/JsonSerializableCollection.php
+++ b/shared/lib/Json/JsonSerializableCollection.php
@@ -34,7 +34,7 @@ abstract class JsonSerializableCollection extends CollectionAbstract implements
 		if (in_array($this->typeValue, $this->primitiveTypes)) {
 			if ($this->associative) {
 				foreach ($data as $key => $value) {
-					$this[$key] = $value;
+					$this[$this->normalizeKey($key)] = $value;
 				}
 			} else {
 				foreach ($data as $value) {
@@ -43,14 +43,24 @@ abstract class JsonSerializableCollection extends CollectionAbstract implements
 			}
 		}
 
-		if (!in_array($this->typeValue, $this->primitiveTypes) && class_exists($this->typeValue)) {
+		if (!in_array($this->typeValue, $this->primitiveTypes) && is_subclass_of($this->typeValue, \BackedEnum::class)) {
+			if ($this->associative) {
+				foreach ($data as $key => $value) {
+					$this[$this->normalizeKey($key)] = ($this->typeValue)::from($value);
+				}
+			} else {
+				foreach ($data as $value) {
+					$this[] = ($this->typeValue)::from($value);
+				}
+			}
+		} elseif (!in_array($this->typeValue, $this->primitiveTypes) && class_exists($this->typeValue)) {
 			$reflection = new \ReflectionClass($this->typeValue);
 			if ($reflection->implementsInterface(JsonDeserializable::class)) {
 				if ($this->associative) {
 					foreach ($data as $key => $value) {
 						$instance = $reflection->newInstance();
 						/** @var JsonDeserializable $instance */
-						$this[$key] = $instance->jsonDeserialize($value);
+						$this[$this->normalizeKey($key)] = $instance->jsonDeserialize($value);
 					}
 				} else {
 					foreach ($data as $value) {
@@ -65,4 +75,13 @@ abstract class JsonSerializableCollection extends CollectionAbstract implements
 		return $this;
 	}
 
+	/**
+	 * JSON round trips turn numeric string keys into integers (and list-shaped
+	 * payloads carry integer keys), which a string-keyed collection would
+	 * otherwise reject on offsetSet.
+	 */
+	private function normalizeKey(int|string $key): int|string {
+		return $this->typeKey === self::TYPE_STRING ? (string)$key : $key;
+	}
+
 }
\ No newline at end of file