diff --git a/src/Decompiler/Analysis/CallRewriter.cs b/src/Decompiler/Analysis/CallRewriter.cs
index 0f9395d901..0a96796e15 100644
--- a/src/Decompiler/Analysis/CallRewriter.cs
+++ b/src/Decompiler/Analysis/CallRewriter.cs
@@ -51,7 +51,7 @@ public CallRewriter(IPlatform platform, ProgramDataFlow mpprocflow, IDecompilerE
 
 		public static void Rewrite(
             IPlatform platform, 
-            List<SsaTransform> ssts,
+            IReadOnlyCollection<SsaTransform> ssts,
             ProgramDataFlow summaries,
             IDecompilerEventListener eventListener)
 		{
diff --git a/src/Decompiler/Analysis/DataFlowAnalysis.cs b/src/Decompiler/Analysis/DataFlowAnalysis.cs
index 8bd19c6d62..351d3e1a4e 100644
--- a/src/Decompiler/Analysis/DataFlowAnalysis.cs
+++ b/src/Decompiler/Analysis/DataFlowAnalysis.cs
@@ -18,9 +18,8 @@
  */
 #endregion
 
+using Reko.Concurrent;
 using Reko.Core;
-using Reko.Core.Code;
-using Reko.Core.Expressions;
 using Reko.Core.Graphs;
 using Reko.Core.Hll.C;
 using Reko.Core.Output;
@@ -28,6 +27,7 @@
 using Reko.Core.Types;
 using Reko.Services;
 using System;
+using System.Collections.Concurrent;
 using System.Collections.Generic;
 using System.Diagnostics;
 using System.IO;
@@ -112,11 +112,11 @@ public void AnalyzeProgram()
         /// Summarizes the net effect each procedure has on registers,
         /// then removes trashed registers that aren't live-out.
         /// </summary>
-        public List<SsaTransform> UntangleProcedures()
+        public IReadOnlyCollection<SsaTransform> UntangleProcedures()
         {
             eventListener.Progress.ShowProgress("Rewriting procedures.", 0, Program.Procedures.Count);
 
-            var ssts = new List<SsaTransform>();
+            IReadOnlyCollection<SsaTransform> ssts = Array.Empty<SsaTransform>();
             IntraBlockDeadRegisters.Apply(Program, eventListener);
             if (eventListener.IsCanceled())
                 return ssts;
@@ -171,7 +171,6 @@ public List<SsaTransform> RewriteProceduresToSsa()
             var ssts = new List<SsaTransform>();
             var sccs = SccFinder.Condense(new ProcedureGraph(Program));
             var sccWorkers = sccs.Members.Values.Select(CreateSccWorker);
-            //$TODO: make a TaskTree out of this.
             foreach (var worker in sccWorkers)
             {
                 if (eventListener.IsCanceled())
@@ -182,6 +181,28 @@ public List<SsaTransform> RewriteProceduresToSsa()
             return ssts;
         }
 
+        public IReadOnlyCollection<SsaTransform> RewriteProceduresToSsa_Concurrent()
+        {
+            var ssts = new ConcurrentQueue<SsaTransform>();
+            var sccs = SccFinder.Condense(new ProcedureGraph(Program));
+            var coordinator = new SccWorkerCoordinator<Procedure>(sccs, eventListener, procs =>
+            {
+                Debug.Print("== Working on {0}", string.Join(",", procs.Select(p => p.Name)));
+                if (eventListener.IsCanceled())
+                    return;
+                var worker = CreateSccWorker(procs);
+                var sccSsts = worker.Transform();
+                foreach (var sccSst in sccSsts)
+                {
+                    ssts.Enqueue(sccSst);
+                }
+                Debug.Print("== Done with {0}", string.Join(",", procs.Select(p => p.Name)));
+
+            });
+            coordinator.RunAsync().Wait();
+            return ssts;
+        }
+
         private SccWorker CreateSccWorker(Procedure[] scc)
         {
             return new SccWorker(this, scc, this.dynamicLinker, this.services);
@@ -193,7 +214,7 @@ private SccWorker CreateSccWorker(Procedure[] scc)
         /// trees out of the simple, close-to-the-machine code generated by
         /// the disassembly.
         /// </summary>
-        public void BuildExpressionTrees(List<SsaTransform> ssts)
+        public void BuildExpressionTrees(IReadOnlyCollection<SsaTransform> ssts)
         {
             eventListener.Progress.ShowProgress("Building expressions.", 0, Program.Procedures.Count);
             foreach (var sst in ssts)
diff --git a/src/Decompiler/Decompiler.cs b/src/Decompiler/Decompiler.cs
index 1260ef453e..6643b1c5e0 100644
--- a/src/Decompiler/Decompiler.cs
+++ b/src/Decompiler/Decompiler.cs
@@ -104,7 +104,7 @@ public virtual void AnalyzeDataFlow()
                     var ir = new DynamicLinker(project, program, eventListener);
                     var dfa = new DataFlowAnalysis(program, ir, services);
                     dfa.ClearTestFiles();
-                    var ssas = new List<SsaTransform>();
+                    IReadOnlyCollection<SsaTransform> ssas = new List<SsaTransform>();
                     if (program.NeedsSsaTransform)
                     {
                         eventListener.Progress.ShowStatus("Performing interprocedural analysis.");