diff --git a/src/NzbDrone.Common/Extensions/PathExtensions.cs b/src/NzbDrone.Common/Extensions/PathExtensions.cs
index 8f4c0b22d..1ce4aef40 100644
--- a/src/NzbDrone.Common/Extensions/PathExtensions.cs
+++ b/src/NzbDrone.Common/Extensions/PathExtensions.cs
@@ -170,6 +170,11 @@ namespace NzbDrone.Common.Extensions
 
         public static bool ContainsInvalidPathChars(this string text)
         {
+            if (text.IsNullOrWhiteSpace())
+            {
+                throw new ArgumentNullException("text");
+            }
+
             return text.IndexOfAny(Path.GetInvalidPathChars()) >= 0;
         }
 
diff --git a/src/NzbDrone.Core.Test/HealthCheck/Checks/RootFolderCheckFixture.cs b/src/NzbDrone.Core.Test/HealthCheck/Checks/RootFolderCheckFixture.cs
index 80e388d02..7f5cefc17 100644
--- a/src/NzbDrone.Core.Test/HealthCheck/Checks/RootFolderCheckFixture.cs
+++ b/src/NzbDrone.Core.Test/HealthCheck/Checks/RootFolderCheckFixture.cs
@@ -7,7 +7,9 @@ using NzbDrone.Common.Disk;
 using NzbDrone.Core.HealthCheck.Checks;
 using NzbDrone.Core.Localization;
 using NzbDrone.Core.Movies;
+using NzbDrone.Core.RootFolders;
 using NzbDrone.Core.Test.Framework;
+using NzbDrone.Test.Common;
 
 namespace NzbDrone.Core.Test.HealthCheck.Checks
 {
@@ -22,7 +24,7 @@ namespace NzbDrone.Core.Test.HealthCheck.Checks
                   .Returns("Some Warning Message");
         }
 
-        private void GivenMissingRootFolder()
+        private void GivenMissingRootFolder(string rootFolderPath)
         {
             var movies = Builder<Movie>.CreateListOfSize(1)
                                         .Build()
@@ -32,9 +34,9 @@ namespace NzbDrone.Core.Test.HealthCheck.Checks
                   .Setup(s => s.AllMoviePaths())
                   .Returns(movies.ToDictionary(x => x.Id, x => x.Path));
 
-            Mocker.GetMock<IDiskProvider>()
-                  .Setup(s => s.GetParentFolder(movies.First().Path))
-                  .Returns(@"C:\Movies");
+            Mocker.GetMock<IRootFolderService>()
+                .Setup(s => s.GetBestRootFolderPath(It.IsAny<string>(), null))
+                .Returns(rootFolderPath);
 
             Mocker.GetMock<IDiskProvider>()
                   .Setup(s => s.FolderExists(It.IsAny<string>()))
@@ -54,7 +56,25 @@ namespace NzbDrone.Core.Test.HealthCheck.Checks
         [Test]
         public void should_return_error_if_movie_parent_is_missing()
         {
-            GivenMissingRootFolder();
+            GivenMissingRootFolder(@"C:\Movies".AsOsAgnostic());
+
+            Subject.Check().ShouldBeError();
+        }
+
+        [Test]
+        public void should_return_error_if_series_path_is_for_posix_os()
+        {
+            WindowsOnly();
+            GivenMissingRootFolder("/mnt/movies");
+
+            Subject.Check().ShouldBeError();
+        }
+
+        [Test]
+        public void should_return_error_if_series_path_is_for_windows()
+        {
+            PosixOnly();
+            GivenMissingRootFolder(@"C:\Movies");
 
             Subject.Check().ShouldBeError();
         }
diff --git a/src/NzbDrone.Core/DiskSpace/DiskSpaceService.cs b/src/NzbDrone.Core/DiskSpace/DiskSpaceService.cs
index f7dcd3893..23f0654a7 100644
--- a/src/NzbDrone.Core/DiskSpace/DiskSpaceService.cs
+++ b/src/NzbDrone.Core/DiskSpace/DiskSpaceService.cs
@@ -5,6 +5,7 @@ using System.Linq;
 using System.Text.RegularExpressions;
 using NLog;
 using NzbDrone.Common.Disk;
+using NzbDrone.Common.Extensions;
 using NzbDrone.Core.Movies;
 
 namespace NzbDrone.Core.DiskSpace
@@ -43,7 +44,7 @@ namespace NzbDrone.Core.DiskSpace
         private IEnumerable<string> GetMoviesRootPaths()
         {
             return _movieService.AllMoviePaths()
-                .Where(s => _diskProvider.FolderExists(s.Value))
+                .Where(s => s.Value.IsPathValid(PathValidationType.CurrentOs) && _diskProvider.FolderExists(s.Value))
                 .Select(s => _diskProvider.GetPathRoot(s.Value))
                 .Distinct();
         }
diff --git a/src/NzbDrone.Core/HealthCheck/Checks/RootFolderCheck.cs b/src/NzbDrone.Core/HealthCheck/Checks/RootFolderCheck.cs
index b991adfcd..b694ddb4f 100644
--- a/src/NzbDrone.Core/HealthCheck/Checks/RootFolderCheck.cs
+++ b/src/NzbDrone.Core/HealthCheck/Checks/RootFolderCheck.cs
@@ -1,5 +1,6 @@
 using System.Linq;
 using NzbDrone.Common.Disk;
+using NzbDrone.Common.Extensions;
 using NzbDrone.Core.Localization;
 using NzbDrone.Core.MediaFiles.Events;
 using NzbDrone.Core.Movies;
@@ -32,7 +33,7 @@ namespace NzbDrone.Core.HealthCheck.Checks
                 .Select(s => _rootFolderService.GetBestRootFolderPath(s.Value))
                 .Distinct();
 
-            var missingRootFolders = rootFolders.Where(s => !_diskProvider.FolderExists(s))
+            var missingRootFolders = rootFolders.Where(s => !s.IsPathValid(PathValidationType.CurrentOs) || !_diskProvider.FolderExists(s))
                 .ToList();
 
             if (missingRootFolders.Any())
diff --git a/src/NzbDrone.Core/RootFolders/RootFolderService.cs b/src/NzbDrone.Core/RootFolders/RootFolderService.cs
index e5cbdb9b8..a77fbc165 100644
--- a/src/NzbDrone.Core/RootFolders/RootFolderService.cs
+++ b/src/NzbDrone.Core/RootFolders/RootFolderService.cs
@@ -188,10 +188,12 @@ namespace NzbDrone.Core.RootFolders
 
             if (possibleRootFolder == null)
             {
-                return _diskProvider.GetParentFolder(path);
+                var osPath = new OsPath(path);
+
+                return osPath.Directory.ToString();
             }
 
-            return possibleRootFolder.Path;
+            return possibleRootFolder?.Path;
         }
 
         private void GetDetails(RootFolder rootFolder, Dictionary<int, string> moviePaths, bool timeout)