diff --git a/Shoko.Server/Filters/FilterExtensions.cs b/Shoko.Server/Filters/FilterExtensions.cs
index 811dc24cf..fe26a76d5 100644
--- a/Shoko.Server/Filters/FilterExtensions.cs
+++ b/Shoko.Server/Filters/FilterExtensions.cs
@@ -54,7 +54,7 @@ public static Filterable ToFilterable(this SVR_AnimeSeries series)
             TagsDelegate = () =>
                 series.AniDB_Anime?.Tags.Select(a => a.TagName).ToHashSet() ?? [],
             CustomTagsDelegate = () =>
-                series.AniDB_Anime?.CustomTags.Select(a => a.TagName).ToHashSet() ?? [],
+                series.AniDB_Anime?.CustomTags.Select(a => a.TagName).ToHashSet(StringComparer.InvariantCultureIgnoreCase) ?? [],
             YearsDelegate = () =>
                 series.Years,
             SeasonsDelegate = () =>