diff --git a/src/Verify/Serialization/Converters/DictionaryConverter.cs b/src/Verify/Serialization/Converters/DictionaryConverter.cs
index 44fa839d87..2e2fc92fb2 100644
--- a/src/Verify/Serialization/Converters/DictionaryConverter.cs
+++ b/src/Verify/Serialization/Converters/DictionaryConverter.cs
@@ -1,5 +1,4 @@
-using System.Collections.Immutable;
-using System.Collections.ObjectModel;
+using System.Collections.ObjectModel;
 using Newtonsoft.Json;
 using VerifyTests;
 
@@ -43,7 +42,7 @@ public override void WriteJson(JsonWriter writer, object value, JsonSerializer s
         var keyType = genericArguments.First();
         var definition = type.GetGenericTypeDefinition();
         if (definition == typeof(SortedDictionary<,>) ||
-            definition == typeof(ImmutableSortedDictionary<,>) )
+            definition.Name == "ImmutableSortedDictionary`2")
         {
             if (keyType == typeof(string))
             {