diff --git a/src/NzbDrone.Common/DiskProvider.cs b/src/NzbDrone.Common/DiskProvider.cs
index ef5242fc7..13379c91c 100644
--- a/src/NzbDrone.Common/DiskProvider.cs
+++ b/src/NzbDrone.Common/DiskProvider.cs
@@ -506,10 +506,7 @@ public string GetVolumeLabel(string path)
 
         private static long DriveFreeSpaceEx(string folderName)
         {
-            if (string.IsNullOrEmpty(folderName))
-            {
-                throw new ArgumentNullException("folderName");
-            }
+            Ensure.That(folderName, () => folderName).IsValidPath();
 
             if (!folderName.EndsWith("\\"))
             {
@@ -530,10 +527,7 @@ private static long DriveFreeSpaceEx(string folderName)
 
         private static long DriveTotalSizeEx(string folderName)
         {
-            if (string.IsNullOrEmpty(folderName))
-            {
-                throw new ArgumentNullException("folderName");
-            }
+            Ensure.That(folderName, () => folderName).IsValidPath();
 
             if (!folderName.EndsWith("\\"))
             {
diff --git a/src/NzbDrone.Core/Configuration/ConfigService.cs b/src/NzbDrone.Core/Configuration/ConfigService.cs
index 89f542670..373385aa2 100644
--- a/src/NzbDrone.Core/Configuration/ConfigService.cs
+++ b/src/NzbDrone.Core/Configuration/ConfigService.cs
@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.Linq;
 using NLog;
+using NzbDrone.Common.EnsureThat;
 using NzbDrone.Core.Configuration.Events;
 using NzbDrone.Core.Download;
 using NzbDrone.Core.Download.Clients.Nzbget;
@@ -305,9 +306,11 @@ public T GetValueEnum<T>(string key, T defaultValue)
 
         public string GetValue(string key, object defaultValue, bool persist = false)
         {
+            key = key.ToLowerInvariant();
+            Ensure.That(key, () => key).IsNotNullOrWhiteSpace();
+
             EnsureCache();
 
-            key = key.ToLowerInvariant();
             string dbValue;
 
             if (_cache.TryGetValue(key, out dbValue) && dbValue != null && !String.IsNullOrEmpty(dbValue))
@@ -336,11 +339,6 @@ public void SetValue(string key, string value)
         {
             key = key.ToLowerInvariant();
 
-            if (String.IsNullOrEmpty(key))
-                throw new ArgumentOutOfRangeException("key");
-            if (value == null)
-                throw new ArgumentNullException("key");
-
             _logger.Trace("Writing Setting to file. Key:'{0}' Value:'{1}'", key, value);
 
             var dbValue = _repository.Get(key);
diff --git a/src/NzbDrone.Core/DataAugmentation/Xem/XemService.cs b/src/NzbDrone.Core/DataAugmentation/Xem/XemService.cs
index c7e7b3441..f8dfed427 100644
--- a/src/NzbDrone.Core/DataAugmentation/Xem/XemService.cs
+++ b/src/NzbDrone.Core/DataAugmentation/Xem/XemService.cs
@@ -20,7 +20,6 @@ public XemService(IEpisodeService episodeService,
                            IXemProxy xemProxy,
                            ISeriesService seriesService, ICacheManger cacheManger, Logger logger)
         {
-            if (seriesService == null) throw new ArgumentNullException("seriesService");
             _episodeService = episodeService;
             _xemProxy = xemProxy;
             _seriesService = seriesService;
diff --git a/src/NzbDrone.Core/Fluent.cs b/src/NzbDrone.Core/Fluent.cs
index 8ec82a8ab..b7ae4824b 100644
--- a/src/NzbDrone.Core/Fluent.cs
+++ b/src/NzbDrone.Core/Fluent.cs
@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.Linq;
 using System.Text;
+using NzbDrone.Common.EnsureThat;
 
 namespace NzbDrone.Core
 {
@@ -9,8 +10,8 @@ public static class Fluent
     {
         public static string WithDefault(this string actual, object defaultValue)
         {
-            if (defaultValue == null)
-                throw new ArgumentNullException("defaultValue");
+            Ensure.That(defaultValue, () => defaultValue).IsNotNull();
+
             if (String.IsNullOrWhiteSpace(actual))
             {
                 return defaultValue.ToString();