diff --git a/Node/Workers/FlowWorker.cs b/Node/Workers/FlowWorker.cs
index ea382e875..4e460e6ce 100644
--- a/Node/Workers/FlowWorker.cs
+++ b/Node/Workers/FlowWorker.cs
@@ -8,6 +8,7 @@
 using FileFlows.ServerShared.Workers;
 using FileFlows.Shared.Models;
 using Jint.Native.Json;
+using System.Collections.Concurrent;
 
 namespace FileFlows.Node.Workers;
 
@@ -15,7 +16,7 @@ namespace FileFlows.Node.Workers;
 /// <summary>
 /// A flow worker executes a flow and start a flow runner
 /// </summary>
-public class FlowWorker : Worker
+public class FlowWorker : Worker, IWorkerThatUsesTempDirectories
 {
     /// <summary>
     /// A unique identifier to identify the flow worker
@@ -25,7 +26,13 @@ public class FlowWorker : Worker
     public readonly Guid Uid = Guid.NewGuid();
 
     private readonly string _configKeyDefault = Guid.NewGuid().ToString();
-    
+
+    public bool IsTempDirectoryInUse(string directory)
+    {
+        var tempDirectoryInUse = ExecutingRunners.Keys.Any(t => directory.EndsWith(t.ToString(), StringComparison.OrdinalIgnoreCase));
+        return tempDirectoryInUse;
+    }
+
     /// <summary>
     /// Gets if the config encryption key 
     /// </summary>
@@ -78,7 +85,10 @@ private bool GetConfigNoEncrypt(ProcessingNode node)
     private static FlowWorker? Instance;
 
     private readonly Mutex mutex = new Mutex();
-    private readonly List<Guid> ExecutingRunners = new ();
+    /// <summary>
+    /// Concurrent because we have the TempFileCleaner running in parallel
+    /// </summary>
+    private readonly ConcurrentDictionary<Guid, object?> ExecutingRunners = new ();
 
     private const int DEFAULT_INTERVAL = 10;
     
@@ -506,7 +516,7 @@ private void AddExecutingRunner(Guid uid)
         mutex.WaitOne();
         try
         {
-            ExecutingRunners.Add(uid);
+            ExecutingRunners.TryAdd(uid, null);
         }
         finally
         {
@@ -525,8 +535,10 @@ private void RemoveExecutingRunner(Guid uid)
         mutex.WaitOne();
         try
         {
-            if (ExecutingRunners.Contains(uid))
-                ExecutingRunners.Remove(uid);
+            if (ExecutingRunners.TryRemove(uid, out var _))
+            {
+
+            }
             else
             {
                 Logger.Instance?.ILog("Executing runner not in list: " + uid +" => " + string.Join(",", ExecutingRunners.Select(x => x.ToString())));
@@ -742,5 +754,4 @@ private async Task<bool> UpdateConfiguration(ProcessingNode node)
         return true;
 
     }
-
 }
diff --git a/ServerShared/IWorkerThatUsesTempDirectories.cs b/ServerShared/IWorkerThatUsesTempDirectories.cs
new file mode 100644
index 000000000..48dbdb8b9
--- /dev/null
+++ b/ServerShared/IWorkerThatUsesTempDirectories.cs
@@ -0,0 +1,7 @@
+namespace FileFlows.ServerShared
+{
+    public interface IWorkerThatUsesTempDirectories
+    {
+        public bool IsTempDirectoryInUse(string directory);
+    }
+}
diff --git a/ServerShared/Workers/TempFileCleaner.cs b/ServerShared/Workers/TempFileCleaner.cs
index 32136fcd3..428f2eaea 100644
--- a/ServerShared/Workers/TempFileCleaner.cs
+++ b/ServerShared/Workers/TempFileCleaner.cs
@@ -8,14 +8,17 @@ namespace FileFlows.ServerShared.Workers;
 public class TempFileCleaner:Worker
 {
     private string nodeAddress;
-    
+    private readonly IWorkerThatUsesTempDirectories workerThatUsesTempDirectories;
+
     /// <summary>
     /// Constructs a temp file cleaner
     /// <param name="nodeAddress">The name of the node</param>
+    /// <param name="workerThatUsesTempDirectories">The worker that uses temp directories, this is used to verify that a temp directory should not be removed while still in use</param>"
     /// </summary>
-    public TempFileCleaner(string nodeAddress) : base(ScheduleType.Daily, 5)
+    public TempFileCleaner(string nodeAddress, IWorkerThatUsesTempDirectories workerThatUsesTempDirectories) : base(ScheduleType.Daily, 5)
     {
         this.nodeAddress = nodeAddress;
+        this.workerThatUsesTempDirectories = workerThatUsesTempDirectories;
         Trigger();
     }
 
@@ -37,6 +40,9 @@ protected sealed override void Execute()
         Logger.Instance?.ILog("About to clean temporary directory: " + tempDir.FullName);
         foreach (var dir in tempDir.GetDirectories())
         {
+            if (workerThatUsesTempDirectories.IsTempDirectoryInUse(dir.Name))
+                continue;
+
             if (dir.CreationTimeUtc < DateTime.UtcNow.AddDays(-1))
             {
                 try