diff --git a/src/Shouldly.Tests/ConventionTests/ApprovePublicAPI.ShouldlyApi.approved.cs b/src/Shouldly.Tests/ConventionTests/ApprovePublicAPI.ShouldlyApi.approved.cs
index 76e307bab..63b7096e0 100644
--- a/src/Shouldly.Tests/ConventionTests/ApprovePublicAPI.ShouldlyApi.approved.cs
+++ b/src/Shouldly.Tests/ConventionTests/ApprovePublicAPI.ShouldlyApi.approved.cs
@@ -684,6 +684,7 @@ public class KnownDiffTools
         public readonly Shouldly.Configuration.DiffTool KDiff3;
         public readonly Shouldly.Configuration.DiffTool P4Merge;
         public readonly Shouldly.Configuration.DiffTool TortoiseGitMerge;
+        public readonly Shouldly.Configuration.DiffTool WinMerge;
         public KnownDiffTools() { }
         public static Shouldly.Configuration.KnownDiffTools Instance { get; }
     }
diff --git a/src/Shouldly/Configuration/KnownDiffTools.cs b/src/Shouldly/Configuration/KnownDiffTools.cs
index 8ad3c4341..611f44bef 100644
--- a/src/Shouldly/Configuration/KnownDiffTools.cs
+++ b/src/Shouldly/Configuration/KnownDiffTools.cs
@@ -19,6 +19,8 @@ public class KnownDiffTools
         [UsedImplicitly]
         public readonly DiffTool TortoiseGitMerge = new DiffTool("Tortoise Git Merge", @"TortoiseGit\bin\TortoiseGitMerge.exe", TortoiseGitMergeArgs);
         [UsedImplicitly]
+        public readonly DiffTool WinMerge = new DiffTool("WinMerge", @"WinMerge\WinMergeU.exe", WinMergeArgs);
+        [UsedImplicitly]
         public readonly DiffTool CurrentVisualStudio = new CurrentlyRunningVisualStudioDiffTool();
 
         public static KnownDiffTools Instance { get; } = new KnownDiffTools();
@@ -57,6 +59,14 @@ static string TortoiseGitMergeArgs(string received, string approved, bool approv
 
             return $"\"{received}\" \"{approved}\"";
         }
+
+        static string WinMergeArgs(string received, string approved, bool approvedExists)
+        {
+            if (!approvedExists)
+                File.AppendAllText(approved, string.Empty);
+
+            return $"/u /wl \"{received}\" \"{approved}\" \"{approved}\"";
+        }
     }
 }
 #endif