From a06a73f65f260705954bc9ca3a1e677cfa58890c Mon Sep 17 00:00:00 2001
From: Stef Heyenrath <stef.heyenrath@gmail.com>
Date: Sat, 21 Feb 2026 14:38:14 +0100
Subject: [PATCH] ...

---
 src/WireMock.Net.Minimal/Matchers/FuncMatcher.cs |  1 -
 .../WebSockets/WebSocketBuilder.cs               | 16 ++++++++++++----
 2 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/src/WireMock.Net.Minimal/Matchers/FuncMatcher.cs b/src/WireMock.Net.Minimal/Matchers/FuncMatcher.cs
index 6c34ab88..6884f542 100644
--- a/src/WireMock.Net.Minimal/Matchers/FuncMatcher.cs
+++ b/src/WireMock.Net.Minimal/Matchers/FuncMatcher.cs
@@ -1,6 +1,5 @@
 // Copyright © WireMock.Net
 
-using System;
 using Stef.Validation;
 using WireMock.Extensions;
 
diff --git a/src/WireMock.Net.Minimal/WebSockets/WebSocketBuilder.cs b/src/WireMock.Net.Minimal/WebSockets/WebSocketBuilder.cs
index e02ab59a..c51794d6 100644
--- a/src/WireMock.Net.Minimal/WebSockets/WebSocketBuilder.cs
+++ b/src/WireMock.Net.Minimal/WebSockets/WebSocketBuilder.cs
@@ -278,11 +278,19 @@ internal class WebSocketBuilder(Response response) : IWebSocketBuilder
             }
         }
 
-
-        if (message.MessageType == WebSocketMessageType.Binary && matcher is IBytesMatcher bytesMatcher && message.Bytes != null)
+        if (message.MessageType == WebSocketMessageType.Binary)
         {
-            var result = await bytesMatcher.IsMatchAsync(message.Bytes);
-            return result.IsPerfect();
+            if (matcher is IBytesMatcher bytesMatcher)
+            {
+                var result = await bytesMatcher.IsMatchAsync(message.Bytes);
+                return result.IsPerfect();
+            }
+
+            if (matcher is IFuncMatcher funcMatcher)
+            {
+                var result = funcMatcher.IsMatch(message.Bytes);
+                return result.IsPerfect();
+            }            
         }
 
         return false;