diff --git a/src/NzbDrone.Core/CustomFormats/CustomFormatCalculationService.cs b/src/NzbDrone.Core/CustomFormats/CustomFormatCalculationService.cs
index 383a48f6e..ec673f294 100644
--- a/src/NzbDrone.Core/CustomFormats/CustomFormatCalculationService.cs
+++ b/src/NzbDrone.Core/CustomFormats/CustomFormatCalculationService.cs
@@ -94,7 +94,11 @@ public static List<CustomFormat> ParseCustomFormat(EpisodeFile episodeFile, List
 
         public List<CustomFormat> ParseCustomFormat(ParsedEpisodeInfo episodeInfo, Series series)
         {
-            episodeInfo.ExtraInfo["OriginalLanguage"] = series.OriginalLanguage;
+            if (series?.OriginalLanguage != null)
+            {
+                episodeInfo.ExtraInfo["OriginalLanguage"] = series.OriginalLanguage;
+            }
+
             return ParseCustomFormat(episodeInfo, _formatService.All());
         }