diff --git a/FindDuplicates/FindDuplicates.csproj b/FindDuplicates/FindDuplicates.csproj
index ee11460..8be28bf 100644
--- a/FindDuplicates/FindDuplicates.csproj
+++ b/FindDuplicates/FindDuplicates.csproj
@@ -6,7 +6,7 @@
         <ImplicitUsings>enable</ImplicitUsings>
         <Nullable>enable</Nullable>
         <AssemblyName>fdup</AssemblyName>
-        <VersionPrefix>1.0.0</VersionPrefix>
+        <VersionPrefix>1.0.1</VersionPrefix>
         <Authors>Oliver Booth</Authors>
     </PropertyGroup>
 
diff --git a/FindDuplicates/ListCommand.cs b/FindDuplicates/ListCommand.cs
index 01f1f38..f697925 100644
--- a/FindDuplicates/ListCommand.cs
+++ b/FindDuplicates/ListCommand.cs
@@ -1,4 +1,5 @@
-using System.Diagnostics;
+using System.Collections.Concurrent;
+using System.Diagnostics;
 using System.Security.Cryptography;
 using System.Text;
 using Spectre.Console;
@@ -8,7 +9,7 @@ namespace FindDuplicates;
 
 internal sealed class ListCommand : AsyncCommand<ListSettings>
 {
-    private readonly Dictionary<string, List<FileInfo>> _fileHashMap = new();
+    private readonly ConcurrentDictionary<string, List<FileInfo>> _fileHashMap = new();
 
     public override async Task<int> ExecuteAsync(CommandContext context, ListSettings settings)
     {