diff --git a/src/NzbDrone.Core/IndexerSearch/ReleaseSearchService.cs b/src/NzbDrone.Core/IndexerSearch/ReleaseSearchService.cs
index a87cba171d..ed7cf6aee7 100644
--- a/src/NzbDrone.Core/IndexerSearch/ReleaseSearchService.cs
+++ b/src/NzbDrone.Core/IndexerSearch/ReleaseSearchService.cs
@@ -8,6 +8,7 @@
 using NzbDrone.Core.DecisionEngine;
 using NzbDrone.Core.Indexers;
 using NzbDrone.Core.IndexerSearch.Definitions;
+using NzbDrone.Core.Languages;
 using NzbDrone.Core.Movies;
 using NzbDrone.Core.Movies.Translations;
 using NzbDrone.Core.Parser.Model;
@@ -75,7 +76,7 @@ private TSpec Get<TSpec>(Movie movie, bool userInvokedSearch, bool interactiveSe
                 InteractiveSearch = interactiveSearch
             };
 
-            var wantedLanguages = _qualityProfileService.GetAcceptableLanguages(movie.QualityProfileId);
+            var wantedLanguages = new HashSet<Language>(_qualityProfileService.GetAcceptableLanguages(movie.QualityProfileId));
             var translations = _movieTranslationService.GetAllTranslationsForMovieMetadata(movie.MovieMetadataId);
 
             var queryTranslations = new List<string>
diff --git a/src/NzbDrone.Core/Indexers/Newznab/NewznabCategoryFieldOptionsConverter.cs b/src/NzbDrone.Core/Indexers/Newznab/NewznabCategoryFieldOptionsConverter.cs
index 6d1095ca75..d1770273fe 100644
--- a/src/NzbDrone.Core/Indexers/Newznab/NewznabCategoryFieldOptionsConverter.cs
+++ b/src/NzbDrone.Core/Indexers/Newznab/NewznabCategoryFieldOptionsConverter.cs
@@ -9,10 +9,10 @@ public static class NewznabCategoryFieldOptionsConverter
         public static List<FieldSelectOption<int>> GetFieldSelectOptions(List<NewznabCategory> categories)
         {
             // Categories not relevant for Radarr
-            var ignoreCategories = new[] { 1000, 3000, 4000, 6000, 7000 };
+            var ignoreCategories = new HashSet<int> { 1000, 3000, 4000, 6000, 7000 };
 
             // And maybe relevant for specific users
-            var unimportantCategories = new[] { 0, 5000 };
+            var unimportantCategories = new HashSet<int> { 0, 5000 };
 
             var result = new List<FieldSelectOption<int>>();
 
diff --git a/src/NzbDrone.Core/Organizer/FileNameBuilder.cs b/src/NzbDrone.Core/Organizer/FileNameBuilder.cs
index 8c1b395671..78ee1df901 100644
--- a/src/NzbDrone.Core/Organizer/FileNameBuilder.cs
+++ b/src/NzbDrone.Core/Organizer/FileNameBuilder.cs
@@ -451,12 +451,12 @@ private static string GetCustomFormatsToken(List<CustomFormat> customFormats, st
             {
                 if (filter.StartsWith("-"))
                 {
-                    var splitFilter = filter.Substring(1).Split(',');
+                    var splitFilter = new HashSet<string>(filter.Substring(1).Split(','));
                     filteredTokens = tokens.Where(c => !splitFilter.Contains(c.Name)).ToList();
                 }
                 else
                 {
-                    var splitFilter = filter.Split(',');
+                    var splitFilter = new HashSet<string>(filter.Split(','));
                     filteredTokens = tokens.Where(c => splitFilter.Contains(c.Name)).ToList();
                 }
             }