diff --git a/src/NzbDrone.Core/Extras/Metadata/Consumers/Xbmc/XbmcMetadata.cs b/src/NzbDrone.Core/Extras/Metadata/Consumers/Xbmc/XbmcMetadata.cs
index 85485bc87..afece96f2 100644
--- a/src/NzbDrone.Core/Extras/Metadata/Consumers/Xbmc/XbmcMetadata.cs
+++ b/src/NzbDrone.Core/Extras/Metadata/Consumers/Xbmc/XbmcMetadata.cs
@@ -104,7 +104,7 @@ namespace NzbDrone.Core.Extras.Metadata.Consumers.Xbmc
                 return metadata;
             }
 
-            if (filename.Equals("tvshow.nfo", StringComparison.InvariantCultureIgnoreCase))
+            if (filename.Equals("tvshow.nfo", StringComparison.OrdinalIgnoreCase))
             {
                 metadata.Type = MetadataType.SeriesMetadata;
                 return metadata;
@@ -114,7 +114,7 @@ namespace NzbDrone.Core.Extras.Metadata.Consumers.Xbmc
 
             if (parseResult != null &&
                 !parseResult.FullSeason &&
-                Path.GetExtension(filename) == ".nfo")
+                Path.GetExtension(filename).Equals(".nfo", StringComparison.OrdinalIgnoreCase))
             {
                 metadata.Type = MetadataType.EpisodeMetadata;
                 return metadata;
diff --git a/src/NzbDrone.Core/Extras/Others/OtherExtraService.cs b/src/NzbDrone.Core/Extras/Others/OtherExtraService.cs
index f3e331c30..18370b0fe 100644
--- a/src/NzbDrone.Core/Extras/Others/OtherExtraService.cs
+++ b/src/NzbDrone.Core/Extras/Others/OtherExtraService.cs
@@ -1,4 +1,5 @@
-using System.Collections.Generic;
+using System;
+using System.Collections.Generic;
 using System.IO;
 using System.Linq;
 using NLog;
@@ -65,7 +66,7 @@ namespace NzbDrone.Core.Extras.Others
         public override ExtraFile Import(Series series, EpisodeFile episodeFile, string path, string extension, bool readOnly)
         {
             // If the extension is .nfo we need to change it to .nfo-orig
-            if (Path.GetExtension(path).Equals(".nfo"))
+            if (Path.GetExtension(path).Equals(".nfo", StringComparison.OrdinalIgnoreCase))
             {
                 extension += "-orig";
             }
diff --git a/src/NzbDrone.Core/Extras/Subtitles/SubtitleFileExtensions.cs b/src/NzbDrone.Core/Extras/Subtitles/SubtitleFileExtensions.cs
index 423d14656..f52b0f162 100644
--- a/src/NzbDrone.Core/Extras/Subtitles/SubtitleFileExtensions.cs
+++ b/src/NzbDrone.Core/Extras/Subtitles/SubtitleFileExtensions.cs
@@ -1,4 +1,5 @@
-using System.Collections.Generic;
+using System;
+using System.Collections.Generic;
 
 namespace NzbDrone.Core.Extras.Subtitles
 {
@@ -8,7 +9,7 @@ namespace NzbDrone.Core.Extras.Subtitles
 
         static SubtitleFileExtensions()
         {
-            _fileExtensions = new HashSet<string>
+            _fileExtensions = new HashSet<string>(StringComparer.OrdinalIgnoreCase)
                               {
                                   ".aqt",
                                   ".ass",
diff --git a/src/NzbDrone.Core/MediaFiles/DiskScanService.cs b/src/NzbDrone.Core/MediaFiles/DiskScanService.cs
index 2f6ba4b25..942897004 100644
--- a/src/NzbDrone.Core/MediaFiles/DiskScanService.cs
+++ b/src/NzbDrone.Core/MediaFiles/DiskScanService.cs
@@ -135,7 +135,7 @@ namespace NzbDrone.Core.MediaFiles
             var searchOption = allDirectories ? SearchOption.AllDirectories : SearchOption.TopDirectoryOnly;
             var filesOnDisk = _diskProvider.GetFiles(path, searchOption).ToList();
 
-            var mediaFileList = filesOnDisk.Where(file => MediaFileExtensions.Extensions.Contains(Path.GetExtension(file).ToLower()))
+            var mediaFileList = filesOnDisk.Where(file => MediaFileExtensions.Extensions.Contains(Path.GetExtension(file)))
                                            .ToList();
 
             _logger.Trace("{0} files were found in {1}", filesOnDisk.Count, path);
@@ -150,7 +150,7 @@ namespace NzbDrone.Core.MediaFiles
             var searchOption = allDirectories ? SearchOption.AllDirectories : SearchOption.TopDirectoryOnly;
             var filesOnDisk = _diskProvider.GetFiles(path, searchOption).ToList();
 
-            var mediaFileList = filesOnDisk.Where(file => !MediaFileExtensions.Extensions.Contains(Path.GetExtension(file).ToLower()))
+            var mediaFileList = filesOnDisk.Where(file => !MediaFileExtensions.Extensions.Contains(Path.GetExtension(file)))
                                            .ToList();
 
             _logger.Trace("{0} files were found in {1}", filesOnDisk.Count, path);
@@ -184,7 +184,7 @@ namespace NzbDrone.Core.MediaFiles
                 _logger.Warn(ex, "Unable to apply permissions to: " + path);
                 _logger.Debug(ex, ex.Message);
             }
-        }       
+        }
 
         public void Handle(SeriesUpdatedEvent message)
         {
@@ -210,4 +210,4 @@ namespace NzbDrone.Core.MediaFiles
             }
         }
     }
-}
\ No newline at end of file
+}
diff --git a/src/NzbDrone.Core/MediaFiles/DownloadedEpisodesImportService.cs b/src/NzbDrone.Core/MediaFiles/DownloadedEpisodesImportService.cs
index ea7491d62..d29f949e0 100644
--- a/src/NzbDrone.Core/MediaFiles/DownloadedEpisodesImportService.cs
+++ b/src/NzbDrone.Core/MediaFiles/DownloadedEpisodesImportService.cs
@@ -1,14 +1,15 @@
-using System.Collections.Generic;
+using System;
+using System.Collections.Generic;
 using System.IO;
 using System.Linq;
 using NLog;
 using NzbDrone.Common.Disk;
 using NzbDrone.Core.DecisionEngine;
+using NzbDrone.Core.Download;
 using NzbDrone.Core.MediaFiles.EpisodeImport;
 using NzbDrone.Core.Parser;
-using NzbDrone.Core.Tv;
-using NzbDrone.Core.Download;
 using NzbDrone.Core.Parser.Model;
+using NzbDrone.Core.Tv;
 
 namespace NzbDrone.Core.MediaFiles
 {
@@ -101,7 +102,7 @@ namespace NzbDrone.Core.MediaFiles
         public bool ShouldDeleteFolder(DirectoryInfo directoryInfo, Series series)
         {
             var videoFiles = _diskScanService.GetVideoFiles(directoryInfo.FullName);
-            var rarFiles = _diskProvider.GetFiles(directoryInfo.FullName, SearchOption.AllDirectories).Where(f => Path.GetExtension(f) == ".rar");
+            var rarFiles = _diskProvider.GetFiles(directoryInfo.FullName, SearchOption.AllDirectories).Where(f => Path.GetExtension(f).Equals(".rar", StringComparison.OrdinalIgnoreCase));
 
             foreach (var videoFile in videoFiles)
             {
diff --git a/src/NzbDrone.Core/MediaFiles/MediaFileExtensions.cs b/src/NzbDrone.Core/MediaFiles/MediaFileExtensions.cs
index 6a951a3b9..e62e046d3 100644
--- a/src/NzbDrone.Core/MediaFiles/MediaFileExtensions.cs
+++ b/src/NzbDrone.Core/MediaFiles/MediaFileExtensions.cs
@@ -1,4 +1,5 @@
-using System.Collections.Generic;
+using System;
+using System.Collections.Generic;
 using NzbDrone.Core.Qualities;
 
 
@@ -10,7 +11,7 @@ namespace NzbDrone.Core.MediaFiles
 
         static MediaFileExtensions()
         {
-            _fileExtensions = new Dictionary<string, Quality>
+            _fileExtensions = new Dictionary<string, Quality>(StringComparer.OrdinalIgnoreCase)
             {
                 //Unknown
                 { ".webm", Quality.Unknown },
@@ -70,7 +71,7 @@ namespace NzbDrone.Core.MediaFiles
             };
         }
 
-        public static HashSet<string> Extensions => new HashSet<string>(_fileExtensions.Keys);
+        public static HashSet<string> Extensions => new HashSet<string>(_fileExtensions.Keys, StringComparer.OrdinalIgnoreCase);
 
         public static Quality GetQualityForExtension(string extension)
         {