diff --git a/src/NzbDrone.Core/MediaFiles/DownloadedEpisodesImportService.cs b/src/NzbDrone.Core/MediaFiles/DownloadedEpisodesImportService.cs
index 931c13b6a..5368e6faf 100644
--- a/src/NzbDrone.Core/MediaFiles/DownloadedEpisodesImportService.cs
+++ b/src/NzbDrone.Core/MediaFiles/DownloadedEpisodesImportService.cs
@@ -5,6 +5,7 @@ using System.Linq;
 using NLog;
 using NzbDrone.Common.Disk;
 using NzbDrone.Common.EnvironmentInfo;
+using NzbDrone.Common.Extensions;
 using NzbDrone.Core.DecisionEngine;
 using NzbDrone.Core.Download;
 using NzbDrone.Core.MediaFiles.EpisodeImport;
@@ -243,6 +244,20 @@ namespace NzbDrone.Core.MediaFiles
                        };
             }
 
+            var extension = Path.GetExtension(fileInfo.Name);
+
+            if (extension.IsNullOrWhiteSpace() || !MediaFileExtensions.Extensions.Contains(extension))
+            {
+                _logger.Debug("[{0}] has an unsupported extension: '{1}'", fileInfo.FullName, extension);
+
+                return new List<ImportResult>
+                       {
+                           new ImportResult(new ImportDecision(new LocalEpisode { Path = fileInfo.FullName },
+                               new Rejection($"Invalid video file, unsupported extension: '{extension}'")),
+                               $"Invalid video file, unsupported extension: '{extension}'")
+                       };
+            }
+
             if (downloadClientItem == null)
             {
                 if (_diskProvider.IsFileLocked(fileInfo.FullName))
diff --git a/src/NzbDrone.Core/MediaFiles/MediaFileExtensions.cs b/src/NzbDrone.Core/MediaFiles/MediaFileExtensions.cs
index 33fcbf607..1db0e87e6 100644
--- a/src/NzbDrone.Core/MediaFiles/MediaFileExtensions.cs
+++ b/src/NzbDrone.Core/MediaFiles/MediaFileExtensions.cs
@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Collections.Generic;
 using NzbDrone.Core.Qualities;