diff --git a/src/benchmarks/micro/Serializers/DataGenerator.cs b/src/benchmarks/micro/Serializers/DataGenerator.cs
index 852a5ef98f..07efd7e49c 100644
--- a/src/benchmarks/micro/Serializers/DataGenerator.cs
+++ b/src/benchmarks/micro/Serializers/DataGenerator.cs
@@ -4,9 +4,11 @@
 
 using System;
 using System.Collections.Generic;
+using System.Collections.Immutable;
 using System.Linq;
 using System.Xml;
 using System.Xml.Serialization;
+using BenchmarkDotNet.Extensions;
 using MessagePack;
 using ProtoBuf;
 
@@ -34,6 +36,12 @@ internal static T Generate<T>()
                 return (T)(object)new SimpleStructWithProperties { Num = 1, Text = "Foo" };
             if (typeof(T) == typeof(ClassImplementingIXmlSerialiable))
                 return (T)(object)new ClassImplementingIXmlSerialiable { StringValue = "Hello world" };
+            if (typeof(T) == typeof(Dictionary<string, string>))
+                return (T)(object)ValuesGenerator.ArrayOfUniqueValues<string>(100).ToDictionary(value => value);
+            if (typeof(T) == typeof(ImmutableDictionary<string, string>))
+                return (T)(object)ImmutableDictionary.CreateRange(ValuesGenerator.ArrayOfUniqueValues<string>(100).ToDictionary(value => value));
+            if (typeof(T) == typeof(ImmutableSortedDictionary<string, string>))
+                return (T)(object)ImmutableSortedDictionary.CreateRange(ValuesGenerator.ArrayOfUniqueValues<string>(100).ToDictionary(value => value));
 
             throw new NotImplementedException();
         }
diff --git a/src/benchmarks/micro/corefx/System.Text.Json/Serializer/ReadJson.cs b/src/benchmarks/micro/corefx/System.Text.Json/Serializer/ReadJson.cs
index aed4ef2a2c..13845006fd 100644
--- a/src/benchmarks/micro/corefx/System.Text.Json/Serializer/ReadJson.cs
+++ b/src/benchmarks/micro/corefx/System.Text.Json/Serializer/ReadJson.cs
@@ -5,6 +5,8 @@
 using BenchmarkDotNet.Attributes;
 using MicroBenchmarks;
 using MicroBenchmarks.Serializers;
+using System.Collections.Generic;
+using System.Collections.Immutable;
 using System.IO;
 using System.Threading.Tasks;
 
@@ -15,6 +17,9 @@ namespace System.Text.Json.Serialization.Tests
     [GenericTypeArguments(typeof(IndexViewModel))]
     [GenericTypeArguments(typeof(MyEventsListerViewModel))]
     [GenericTypeArguments(typeof(BinaryData))]
+    [GenericTypeArguments(typeof(Dictionary<string, string>))]
+    [GenericTypeArguments(typeof(ImmutableDictionary<string, string>))]
+    [GenericTypeArguments(typeof(ImmutableSortedDictionary<string, string>))]
     public class ReadJson<T>
     {
         private string _serialized;
diff --git a/src/benchmarks/micro/corefx/System.Text.Json/Serializer/WriteJson.cs b/src/benchmarks/micro/corefx/System.Text.Json/Serializer/WriteJson.cs
index 1afceb3c18..e0ca8ad8c3 100644
--- a/src/benchmarks/micro/corefx/System.Text.Json/Serializer/WriteJson.cs
+++ b/src/benchmarks/micro/corefx/System.Text.Json/Serializer/WriteJson.cs
@@ -5,6 +5,8 @@
 using BenchmarkDotNet.Attributes;
 using MicroBenchmarks;
 using MicroBenchmarks.Serializers;
+using System.Collections.Generic;
+using System.Collections.Immutable;
 using System.IO;
 using System.Threading.Tasks;
 
@@ -15,6 +17,9 @@ namespace System.Text.Json.Serialization.Tests
     [GenericTypeArguments(typeof(IndexViewModel))]
     [GenericTypeArguments(typeof(MyEventsListerViewModel))]
     [GenericTypeArguments(typeof(BinaryData))]
+    [GenericTypeArguments(typeof(Dictionary<string, string>))]
+    [GenericTypeArguments(typeof(ImmutableDictionary<string, string>))]
+    [GenericTypeArguments(typeof(ImmutableSortedDictionary<string, string>))]
     public class WriteJson<T>
     {
         private T _value;