diff --git a/Shoko.Server/API/v3/Controllers/ImageController.cs b/Shoko.Server/API/v3/Controllers/ImageController.cs
index 93e9130ff..2888013d8 100644
--- a/Shoko.Server/API/v3/Controllers/ImageController.cs
+++ b/Shoko.Server/API/v3/Controllers/ImageController.cs
@@ -15,6 +15,7 @@
 using Shoko.Server.Settings;
 using Shoko.Server.Utilities;
 
+#nullable enable
 namespace Shoko.Server.API.v3.Controllers;
 
 [ApiController]
@@ -159,7 +160,7 @@ public ActionResult GetRandomImageForType([FromRoute] Image.ImageType imageType)
     public ActionResult<Image> GetRandomImageMetadataForType(
         [FromRoute] Image.ImageType imageType,
         [FromQuery] IncludeOnlyFilter includeRestricted = IncludeOnlyFilter.False,
-        [FromQuery, ModelBinder(typeof(CommaDelimitedModelBinder))] HashSet<SeriesType> seriesType = null,
+        [FromQuery, ModelBinder(typeof(CommaDelimitedModelBinder))] HashSet<SeriesType>? seriesType = null,
         [FromQuery, Range(0, 100)] int maxAttempts = 5
     )
     {
@@ -184,7 +185,7 @@ public ActionResult<Image> GetRandomImageMetadataForType(
 
             var image = new Image(metadata);
             var series = ImageUtils.GetFirstSeriesForImage(metadata);
-            if (series.AniDB_Anime is not { } anime)
+            if (series?.AniDB_Anime is not { } anime)
                 continue;
 
             if (includeRestricted != IncludeOnlyFilter.True)