diff --git a/src/NzbDrone.Common/Extensions/PathExtensions.cs b/src/NzbDrone.Common/Extensions/PathExtensions.cs
index d8c24af8e..e10884da6 100644
--- a/src/NzbDrone.Common/Extensions/PathExtensions.cs
+++ b/src/NzbDrone.Common/Extensions/PathExtensions.cs
@@ -159,6 +159,11 @@ 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 d2eb98316..7df268485 100644
--- a/src/NzbDrone.Core.Test/HealthCheck/Checks/RootFolderCheckFixture.cs
+++ b/src/NzbDrone.Core.Test/HealthCheck/Checks/RootFolderCheckFixture.cs
@@ -8,7 +8,9 @@ using NzbDrone.Core.HealthCheck.Checks;
 using NzbDrone.Core.ImportLists;
 using NzbDrone.Core.Localization;
 using NzbDrone.Core.Music;
+using NzbDrone.Core.RootFolders;
 using NzbDrone.Core.Test.Framework;
+using NzbDrone.Test.Common;
 
 namespace NzbDrone.Core.Test.HealthCheck.Checks
 {
@@ -23,7 +25,7 @@ namespace NzbDrone.Core.Test.HealthCheck.Checks
                   .Returns("Some Warning Message");
         }
 
-        private void GivenMissingRootFolder()
+        private void GivenMissingRootFolder(string rootFolderPath)
         {
             var artist = Builder<Artist>.CreateListOfSize(1)
                                         .Build()
@@ -41,9 +43,9 @@ namespace NzbDrone.Core.Test.HealthCheck.Checks
                 .Setup(s => s.All())
                 .Returns(importList);
 
-            Mocker.GetMock<IDiskProvider>()
-                  .Setup(s => s.GetParentFolder(artist.First().Path))
-                  .Returns(@"C:\Music");
+            Mocker.GetMock<IRootFolderService>()
+                  .Setup(s => s.GetBestRootFolderPath(It.IsAny<string>()))
+                  .Returns(rootFolderPath);
 
             Mocker.GetMock<IDiskProvider>()
                   .Setup(s => s.FolderExists(It.IsAny<string>()))
@@ -67,7 +69,25 @@ namespace NzbDrone.Core.Test.HealthCheck.Checks
         [Test]
         public void should_return_error_if_artist_parent_is_missing()
         {
-            GivenMissingRootFolder();
+            GivenMissingRootFolder(@"C:\Music".AsOsAgnostic());
+
+            Subject.Check().ShouldBeError();
+        }
+
+        [Test]
+        public void should_return_error_if_series_path_is_for_posix_os()
+        {
+            WindowsOnly();
+            GivenMissingRootFolder("/mnt/music");
+
+            Subject.Check().ShouldBeError();
+        }
+
+        [Test]
+        public void should_return_error_if_series_path_is_for_windows()
+        {
+            PosixOnly();
+            GivenMissingRootFolder(@"C:\Music");
 
             Subject.Check().ShouldBeError();
         }
diff --git a/src/NzbDrone.Core/DiskSpace/DiskSpaceService.cs b/src/NzbDrone.Core/DiskSpace/DiskSpaceService.cs
index 5721076c9..4f685c560 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.RootFolders;
 
 namespace NzbDrone.Core.DiskSpace
@@ -33,7 +34,7 @@ namespace NzbDrone.Core.DiskSpace
 
         public List<DiskSpace> GetFreeSpace()
         {
-            var importantRootFolders = _rootFolderService.All().Select(x => x.Path).ToList();
+            var importantRootFolders = GetRootPaths().Distinct().ToList();
 
             var optionalRootFolders = GetFixedDisksRootPaths().Except(importantRootFolders).Distinct().ToList();
 
@@ -42,6 +43,14 @@ namespace NzbDrone.Core.DiskSpace
             return diskSpace;
         }
 
+        private IEnumerable<string> GetRootPaths()
+        {
+            return _rootFolderService.All()
+                .Select(x => x.Path)
+                .Where(path => path.IsPathValid(PathValidationType.CurrentOs) && _diskProvider.FolderExists(path))
+                .Distinct();
+        }
+
         private IEnumerable<string> GetFixedDisksRootPaths()
         {
             return _diskProvider.GetMounts()
diff --git a/src/NzbDrone.Core/HealthCheck/Checks/RootFolderCheck.cs b/src/NzbDrone.Core/HealthCheck/Checks/RootFolderCheck.cs
index a382f77af..978c839c4 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.ImportLists;
 using NzbDrone.Core.Localization;
 using NzbDrone.Core.MediaFiles.Events;
@@ -35,7 +36,7 @@ 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();
 
             missingRootFolders.AddRange(_importListFactory.All()
diff --git a/src/NzbDrone.Core/RootFolders/RootFolderService.cs b/src/NzbDrone.Core/RootFolders/RootFolderService.cs
index a92020bb1..81be2b286 100644
--- a/src/NzbDrone.Core/RootFolders/RootFolderService.cs
+++ b/src/NzbDrone.Core/RootFolders/RootFolderService.cs
@@ -152,10 +152,12 @@ 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)