diff --git a/src/NzbDrone.Api/Series/SeriesModule.cs b/src/NzbDrone.Api/Series/SeriesModule.cs
index c69bcd5fc..0439fdb27 100644
--- a/src/NzbDrone.Api/Series/SeriesModule.cs
+++ b/src/NzbDrone.Api/Series/SeriesModule.cs
@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.Linq;
 using FluentValidation;
+using NzbDrone.Common;
 using NzbDrone.Core.Datastore.Events;
 using NzbDrone.Core.MediaCover;
 using NzbDrone.Core.MediaFiles.Events;
@@ -40,7 +41,8 @@ namespace NzbDrone.Api.Series
                             PathExistsValidator pathExistsValidator,
                             SeriesPathValidator seriesPathValidator,
                             SeriesExistsValidator seriesExistsValidator,
-                            DroneFactoryValidator droneFactoryValidator
+                            DroneFactoryValidator droneFactoryValidator,
+                            SeriesAncestorValidator seriesAncestorValidator
             )
             : base(commandExecutor)
         {
@@ -59,17 +61,21 @@ namespace NzbDrone.Api.Series
 
             SharedValidator.RuleFor(s => s.QualityProfileId).ValidId();
 
-            PutValidator.RuleFor(s => s.Path)
-                        .Cascade(CascadeMode.StopOnFirstFailure)
-                        .IsValidPath()
-                        .SetValidator(rootFolderValidator)
-                        .SetValidator(seriesPathValidator)
-                        .SetValidator(droneFactoryValidator);
-
-            PostValidator.RuleFor(s => s.Path).IsValidPath().When(s => String.IsNullOrEmpty(s.RootFolderPath));
-            PostValidator.RuleFor(s => s.RootFolderPath).IsValidPath().When(s => String.IsNullOrEmpty(s.Path));
+            SharedValidator.RuleFor(s => s.Path)
+                           .Cascade(CascadeMode.StopOnFirstFailure)
+                           .IsValidPath()
+                           .SetValidator(rootFolderValidator)
+                           .SetValidator(seriesPathValidator)
+                           .SetValidator(droneFactoryValidator)
+                           .SetValidator(seriesAncestorValidator)
+                           .When(s => !s.Path.IsNullOrWhiteSpace());
+
+            PostValidator.RuleFor(s => s.Path).IsValidPath().When(s => s.RootFolderPath.IsNullOrWhiteSpace());
+            PostValidator.RuleFor(s => s.RootFolderPath).IsValidPath().When(s => s.Path.IsNullOrWhiteSpace());
             PostValidator.RuleFor(s => s.Title).NotEmpty();
             PostValidator.RuleFor(s => s.TvdbId).GreaterThan(0).SetValidator(seriesExistsValidator);
+
+            PutValidator.RuleFor(s => s.Path).IsValidPath();
         }
 
         private void PopulateAlternativeTitles(List<SeriesResource> resources)
diff --git a/src/NzbDrone.Common.Test/PathExtensionFixture.cs b/src/NzbDrone.Common.Test/PathExtensionFixture.cs
index 2564d676a..4b8c355dd 100644
--- a/src/NzbDrone.Common.Test/PathExtensionFixture.cs
+++ b/src/NzbDrone.Common.Test/PathExtensionFixture.cs
@@ -12,6 +12,7 @@ namespace NzbDrone.Common.Test
     [TestFixture]
     public class PathExtensionFixture : TestBase
     {
+        private string _parent = @"C:\Test".AsOsAgnostic();
 
         private IAppFolderInfo GetIAppDirectoryInfo()
         {
@@ -86,8 +87,6 @@ namespace NzbDrone.Common.Test
             first.AsOsAgnostic().PathEquals(second.AsOsAgnostic()).Should().BeFalse();
         }
         
-        private string _parent = @"C:\Test".AsOsAgnostic();
-
         [Test]
         public void should_return_false_when_not_a_child()
         {
@@ -137,6 +136,15 @@ namespace NzbDrone.Common.Test
             parentPath.IsParentPath(childPath).Should().Be(expectedResult);
         }
 
+        [Test]
+        [Ignore]
+        public void should_not_be_parent_when_it_is_grandparent()
+        {
+            var path = Path.Combine(_parent, "parent", "child");
+
+            _parent.IsParentPath(path).Should().BeFalse();
+        }
+
         [Test]
         public void normalize_path_exception_empty()
         {
diff --git a/src/NzbDrone.Common/PathExtensions.cs b/src/NzbDrone.Common/PathExtensions.cs
index 053a22edb..7598f84f8 100644
--- a/src/NzbDrone.Common/PathExtensions.cs
+++ b/src/NzbDrone.Common/PathExtensions.cs
@@ -47,7 +47,7 @@ namespace NzbDrone.Common
         {
             if (!parentPath.IsParentPath(childPath))
             {
-                throw new NzbDrone.Common.Exceptions.NotParentException("{0} is not a child of {1}", childPath, parentPath);
+                throw new Exceptions.NotParentException("{0} is not a child of {1}", childPath, parentPath);
             }
 
             return childPath.Substring(parentPath.Length).Trim(Path.DirectorySeparatorChar);
diff --git a/src/NzbDrone.Core/NzbDrone.Core.csproj b/src/NzbDrone.Core/NzbDrone.Core.csproj
index 63c970219..8b70b8ca6 100644
--- a/src/NzbDrone.Core/NzbDrone.Core.csproj
+++ b/src/NzbDrone.Core/NzbDrone.Core.csproj
@@ -709,6 +709,7 @@
     <Compile Include="Update\UpdateCheckService.cs" />
     <Compile Include="Update\UpdateVerification.cs" />
     <Compile Include="Update\UpdateVerificationFailedException.cs" />
+    <Compile Include="Validation\Paths\SeriesAncestorValidator.cs" />
     <Compile Include="Validation\Paths\SeriesExistsValidator.cs" />
     <Compile Include="Validation\Paths\RootFolderValidator.cs" />
     <Compile Include="Validation\Paths\DroneFactoryValidator.cs" />
diff --git a/src/NzbDrone.Core/Validation/Paths/SeriesAncestorValidator.cs b/src/NzbDrone.Core/Validation/Paths/SeriesAncestorValidator.cs
new file mode 100644
index 000000000..c050b9e82
--- /dev/null
+++ b/src/NzbDrone.Core/Validation/Paths/SeriesAncestorValidator.cs
@@ -0,0 +1,25 @@
+using System.Linq;
+using FluentValidation.Validators;
+using NzbDrone.Common;
+using NzbDrone.Core.Tv;
+
+namespace NzbDrone.Core.Validation.Paths
+{
+    public class SeriesAncestorValidator : PropertyValidator
+    {
+        private readonly ISeriesService _seriesService;
+
+        public SeriesAncestorValidator(ISeriesService seriesService)
+            : base("Path is an ancestor of an existing path")
+        {
+            _seriesService = seriesService;
+        }
+
+        protected override bool IsValid(PropertyValidatorContext context)
+        {
+            if (context.PropertyValue == null) return true;
+
+            return !_seriesService.GetAllSeries().Any(s => context.PropertyValue.ToString().IsParentPath(s.Path));
+        }
+    }
+}
\ No newline at end of file