diff --git a/XenAdmin/Wizards/PatchingWizard/PatchingWizard_AutoUpdatingPage.cs b/XenAdmin/Wizards/PatchingWizard/PatchingWizard_AutoUpdatingPage.cs
index 234d7d162..e39230e1d 100644
--- a/XenAdmin/Wizards/PatchingWizard/PatchingWizard_AutoUpdatingPage.cs
+++ b/XenAdmin/Wizards/PatchingWizard/PatchingWizard_AutoUpdatingPage.cs
@@ -155,9 +155,9 @@ namespace XenAdmin.Wizards.PatchingWizard
                     var hostsToApply = us.Where(u => u.Value.Contains(patch)).Select(u => u.Key).ToList();
                     hostsToApply.Sort();
 
-                    planActions.Add(new DownloadPatchPlanAction(master.Connection, patch, patchMappings, AllDownloadedPatches));
+                    planActions.Add(new DownloadPatchPlanAction(master.Connection, patch, AllDownloadedPatches));
                     planActions.Add(new UploadPatchToMasterPlanAction(master.Connection, patch, patchMappings, AllDownloadedPatches));
-                    planActions.Add(new PatchPrechecksOnMultipleHostsPlanAction(master.Connection, patch, hostsToApply, patchMappings));
+                    planActions.Add(new PatchPrechecksOnMultipleHostsInAPoolPlanAction(master.Connection, patch, hostsToApply, patchMappings));
 
                     foreach (var host in hostsToApply)
                     {
diff --git a/XenAdmin/Wizards/PatchingWizard/PlanActions/ApplyXenServerPatchPlanAction.cs b/XenAdmin/Wizards/PatchingWizard/PlanActions/ApplyXenServerPatchPlanAction.cs
index ef4e890ba..c9ab65cb1 100644
--- a/XenAdmin/Wizards/PatchingWizard/PlanActions/ApplyXenServerPatchPlanAction.cs
+++ b/XenAdmin/Wizards/PatchingWizard/PlanActions/ApplyXenServerPatchPlanAction.cs
@@ -38,14 +38,14 @@ namespace XenAdmin.Wizards.PatchingWizard.PlanActions
 {
     public class ApplyXenServerPatchPlanAction : PlanActionWithSession
     {
-        private readonly XenRef<Host> host;
+        private readonly Host host;
         private readonly XenServerPatch xenServerPatch;
         private readonly List<PoolPatchMapping> mappings;
 
         public ApplyXenServerPatchPlanAction(Host host, XenServerPatch xenServerPatch, List<PoolPatchMapping> mappings)
             : base(host.Connection, string.Format(Messages.UPDATES_WIZARD_APPLYING_UPDATE, xenServerPatch.Name, host.Name))
         {
-            this.host = new XenRef<Host>(host);
+            this.host = host;
             this.xenServerPatch = xenServerPatch;
             this.mappings = mappings;
         }
@@ -53,7 +53,7 @@ namespace XenAdmin.Wizards.PatchingWizard.PlanActions
         protected override void RunWithSession(ref Session session)
         {
 
-            var mapping = mappings.Find(m => m.XenServerPatch.Uuid == xenServerPatch.Uuid);
+            var mapping = mappings.Find(m => m.XenServerPatch.Uuid == xenServerPatch.Uuid && m.MasterHost == Helpers.GetMaster(host.Connection));
             if (mapping != null && mapping.Pool_patch != null)
             {
                 var patchRef = mapping.Pool_patch;
diff --git a/XenAdmin/Wizards/PatchingWizard/PlanActions/DownloadPatchPlanAction.cs b/XenAdmin/Wizards/PatchingWizard/PlanActions/DownloadPatchPlanAction.cs
index 899565747..7424ec61e 100644
--- a/XenAdmin/Wizards/PatchingWizard/PlanActions/DownloadPatchPlanAction.cs
+++ b/XenAdmin/Wizards/PatchingWizard/PlanActions/DownloadPatchPlanAction.cs
@@ -43,15 +43,13 @@ namespace XenAdmin.Wizards.PatchingWizard.PlanActions
     class DownloadPatchPlanAction : PlanActionWithSession
     {
         private readonly XenServerPatch patch;
-        private readonly List<PoolPatchMapping> mappings;
         private Dictionary<XenServerPatch, string> AllDownloadedPatches = new Dictionary<XenServerPatch, string>();
         private string tempFileName = null;
 
-        public DownloadPatchPlanAction(IXenConnection connection, XenServerPatch patch, List<PoolPatchMapping> mappings, Dictionary<XenServerPatch, string> allDownloadedPatches)
+        public DownloadPatchPlanAction(IXenConnection connection, XenServerPatch patch, Dictionary<XenServerPatch, string> allDownloadedPatches)
             : base(connection, string.Format(Messages.PATCHINGWIZARD_DOWNLOADUPDATE_ACTION_TITLE_WAITING, patch.Name))
         {
             this.patch = patch;
-            this.mappings = mappings;
             this.AllDownloadedPatches = allDownloadedPatches;
         }
 
diff --git a/XenAdmin/Wizards/PatchingWizard/PlanActions/PatchPrechecksOnMultipleHostsAction.cs b/XenAdmin/Wizards/PatchingWizard/PlanActions/PatchPrechecksOnMultipleHostsAction.cs
index 4b8f83c32..8f004e80e 100644
--- a/XenAdmin/Wizards/PatchingWizard/PlanActions/PatchPrechecksOnMultipleHostsAction.cs
+++ b/XenAdmin/Wizards/PatchingWizard/PlanActions/PatchPrechecksOnMultipleHostsAction.cs
@@ -37,17 +37,18 @@ using XenAPI;
 using System.Linq;
 using System.IO;
 using XenAdmin.Network;
-using XenAdmin.Diagnostics.Checks;
+using XenAdmin.Diagnostics.Checks;
+using System.Diagnostics;
 
 namespace XenAdmin.Wizards.PatchingWizard.PlanActions
 {
-    class PatchPrechecksOnMultipleHostsPlanAction : PlanActionWithSession
+    class PatchPrechecksOnMultipleHostsInAPoolPlanAction : PlanActionWithSession
     {
         private readonly XenServerPatch patch;
         private readonly List<PoolPatchMapping> mappings;
         private List<Host> hosts = null;
 
-        public PatchPrechecksOnMultipleHostsPlanAction(IXenConnection connection, XenServerPatch patch, List<Host> hosts, List<PoolPatchMapping> mappings)
+        public PatchPrechecksOnMultipleHostsInAPoolPlanAction(IXenConnection connection, XenServerPatch patch, List<Host> hosts, List<PoolPatchMapping> mappings)
             : base(connection, string.Format("Precheck for {0} in {1}...", patch.Name, connection.Name))
         {
             this.patch = patch;
@@ -57,7 +58,7 @@ namespace XenAdmin.Wizards.PatchingWizard.PlanActions
 
         protected override void RunWithSession(ref Session session)
         {
-            var mapping = mappings.Find(m => m.XenServerPatch == patch);
+            var mapping = mappings.Find(m => m.XenServerPatch == patch && m.MasterHost == Helpers.GetMaster(Connection));
             if (mapping != null && mapping.Pool_patch != null)
             {
                 foreach (var host in hosts)
diff --git a/XenAdmin/Wizards/PatchingWizard/PlanActions/PoolPatchMapping.cs b/XenAdmin/Wizards/PatchingWizard/PlanActions/PoolPatchMapping.cs
index f231137e9..8fb1a88f1 100644
--- a/XenAdmin/Wizards/PatchingWizard/PlanActions/PoolPatchMapping.cs
+++ b/XenAdmin/Wizards/PatchingWizard/PlanActions/PoolPatchMapping.cs
@@ -12,7 +12,7 @@ namespace XenAdmin.Wizards.PatchingWizard.PlanActions
     {
         public XenServerPatch XenServerPatch { get; set; }
         public Pool_patch Pool_patch { get; set; }
-        public Host Host { get; set; }
+        public Host MasterHost { get; set; }
 
         public override bool Equals(object obj)
         {
@@ -24,12 +24,12 @@ namespace XenAdmin.Wizards.PatchingWizard.PlanActions
             return
                 this.XenServerPatch == that.XenServerPatch
                 && this.Pool_patch == that.Pool_patch
-                && this.Host == that.Host;
+                && this.MasterHost == that.MasterHost;
         }
 
         public override int GetHashCode()
         {
-            return XenServerPatch.GetHashCode() ^ Pool_patch.GetHashCode() ^ Host.GetHashCode();
+            return XenServerPatch.GetHashCode() ^ Pool_patch.GetHashCode() ^ MasterHost.GetHashCode();
         }
     }
 }
diff --git a/XenAdmin/Wizards/PatchingWizard/PlanActions/RemoveUpdateFilesFromMaster.cs b/XenAdmin/Wizards/PatchingWizard/PlanActions/RemoveUpdateFilesFromMaster.cs
index e380a5ed6..d4183865d 100644
--- a/XenAdmin/Wizards/PatchingWizard/PlanActions/RemoveUpdateFilesFromMaster.cs
+++ b/XenAdmin/Wizards/PatchingWizard/PlanActions/RemoveUpdateFilesFromMaster.cs
@@ -57,7 +57,7 @@ namespace XenAdmin.Wizards.PatchingWizard.PlanActions
             {
                 Pool_patch poolPatch = null;
 
-                var mapping = patchMappings.FirstOrDefault(pm => pm.Host == master && pm.XenServerPatch == patch);
+                var mapping = patchMappings.FirstOrDefault(pm => pm.MasterHost == master && pm.XenServerPatch == patch);
 
                 if (mapping != null || mapping.Pool_patch != null && mapping.Pool_patch.opaque_ref != null)
                 {
diff --git a/XenAdmin/Wizards/PatchingWizard/PlanActions/UploadPatchToMasterPlanAction.cs b/XenAdmin/Wizards/PatchingWizard/PlanActions/UploadPatchToMasterPlanAction.cs
index d43c9dfa9..cf8d5c89b 100644
--- a/XenAdmin/Wizards/PatchingWizard/PlanActions/UploadPatchToMasterPlanAction.cs
+++ b/XenAdmin/Wizards/PatchingWizard/PlanActions/UploadPatchToMasterPlanAction.cs
@@ -64,7 +64,7 @@ namespace XenAdmin.Wizards.PatchingWizard.PlanActions
             var poolPatches = new List<Pool_patch>(session.Connection.Cache.Pool_patches);
             var conn = session.Connection;
 
-            var existingMapping = mappings.Find(m => m.Host == Helpers.GetMaster(conn) && m.Pool_patch != null && m.XenServerPatch == patch);
+            var existingMapping = mappings.Find(m => m.MasterHost == Helpers.GetMaster(conn) && m.Pool_patch != null && m.XenServerPatch == patch);
             if (existingMapping == null
                 || !poolPatches.Any(p => string.Equals(p.uuid, existingMapping.Pool_patch.uuid, StringComparison.OrdinalIgnoreCase)))
             {
@@ -92,12 +92,12 @@ namespace XenAdmin.Wizards.PatchingWizard.PlanActions
 
                     var newMapping = new PoolPatchMapping()
                     {
-                        Host = Helpers.GetMaster(session.Connection),
+                        MasterHost = Helpers.GetMaster(session.Connection),
                         XenServerPatch = patch,
                         Pool_patch = poolPatch
                     };
 
-                    if (!mappings.Any(m => m.Host == newMapping.Host && m.Pool_patch == newMapping.Pool_patch && m.XenServerPatch == patch))
+                    if (!mappings.Any(m => m.MasterHost == newMapping.MasterHost && m.Pool_patch == newMapping.Pool_patch && m.XenServerPatch == patch))
                         mappings.Add(newMapping);
                 }
                 catch (Exception ex)