diff --git a/custom-metadata-provider-specification.yaml b/custom-metadata-provider-specification.yaml
index 71cbba23a..a0ec172ae 100644
--- a/custom-metadata-provider-specification.yaml
+++ b/custom-metadata-provider-specification.yaml
@@ -127,7 +127,7 @@ components:
         duration:
           type: integer
           format: int64
-          description: Duration in seconds
+          description: Duration in minutes
 
     SeriesMetadata:
       type: object
diff --git a/server/models/User.js b/server/models/User.js
index 36b2eca98..936efde13 100644
--- a/server/models/User.js
+++ b/server/models/User.js
@@ -782,7 +782,14 @@ class User extends Model {
           error: 'Library item not found',
           statusCode: 404
         }
+      } else if (libraryItem.mediaType !== 'book') {
+        Logger.error(`[User] createUpdateMediaProgress: library item ${progressPayload.libraryItemId} is not a book`)
+        return {
+          error: 'Library item is not a book',
+          statusCode: 400
+        }
       }
+
       mediaItemId = libraryItem.media.id
       mediaProgress = libraryItem.media.mediaProgresses?.[0]
     }