diff --git a/src/Ocelot/QueryStrings/AddQueriesToRequest.cs b/src/Ocelot/QueryStrings/AddQueriesToRequest.cs
index 25e9772a..74cc7696 100644
--- a/src/Ocelot/QueryStrings/AddQueriesToRequest.cs
+++ b/src/Ocelot/QueryStrings/AddQueriesToRequest.cs
@@ -7,6 +7,8 @@ using Ocelot.Responses;
 using System.Security.Claims;
 using System.Net.Http;
 using System;
+using Microsoft.Extensions.Primitives;
+using System.Text;
 
 namespace Ocelot.QueryStrings
 {
@@ -45,6 +47,7 @@ namespace Ocelot.QueryStrings
             }
 
             var uriBuilder = new UriBuilder(downstreamRequest.RequestUri);
+
             uriBuilder.Query = ConvertDictionaryToQueryString(queryDictionary);
 
             downstreamRequest.RequestUri = uriBuilder.Uri;
@@ -52,16 +55,43 @@ namespace Ocelot.QueryStrings
             return new OkResponse();
         }
 
-        private Dictionary<string, string> ConvertQueryStringToDictionary(string queryString)
+        private Dictionary<string, StringValues> ConvertQueryStringToDictionary(string queryString)
         {
-            return Microsoft.AspNetCore.WebUtilities.QueryHelpers
-                .ParseQuery(queryString)
-                .ToDictionary(q => q.Key, q => q.Value.FirstOrDefault() ?? string.Empty);
+            var query = Microsoft.AspNetCore.WebUtilities.QueryHelpers
+                .ParseQuery(queryString);
+
+            return query;
         }
 
-        private string ConvertDictionaryToQueryString(Dictionary<string, string> queryDictionary)
+        private string ConvertDictionaryToQueryString(Dictionary<string, StringValues> queryDictionary)
         {
-            return Microsoft.AspNetCore.WebUtilities.QueryHelpers.AddQueryString("", queryDictionary);
+            var builder = new StringBuilder();
+
+            builder.Append("?");
+            
+            int outerCount = 0;
+
+            foreach (var query in queryDictionary)
+            {
+                for (int innerCount = 0; innerCount < query.Value.Count; innerCount++)
+                {
+                    builder.Append($"{query.Key}={query.Value[innerCount]}");
+
+                    if(innerCount < (query.Value.Count - 1))
+                    {
+                        builder.Append("&");
+                    }
+                }
+
+                if(outerCount < (queryDictionary.Count - 1))
+                {
+                    builder.Append("&");
+                }
+
+                outerCount++;
+            }
+
+            return builder.ToString();
         }
     }
 }
\ No newline at end of file
diff --git a/test/Ocelot.AcceptanceTests/ClaimsToQueryStringForwardingTests.cs b/test/Ocelot.AcceptanceTests/ClaimsToQueryStringForwardingTests.cs
index f73a360e..1b9469e1 100644
--- a/test/Ocelot.AcceptanceTests/ClaimsToQueryStringForwardingTests.cs
+++ b/test/Ocelot.AcceptanceTests/ClaimsToQueryStringForwardingTests.cs
@@ -19,6 +19,7 @@ namespace Ocelot.AcceptanceTests
 {
     using IdentityServer4;
     using IdentityServer4.Test;
+    using Shouldly;
 
     public class ClaimsToQueryStringForwardingTests : IDisposable
     {
@@ -27,6 +28,7 @@ namespace Ocelot.AcceptanceTests
         private readonly Steps _steps;
         private Action<IdentityServerAuthenticationOptions> _options;
         private string _identityServerRootUrl = "http://localhost:57888";
+        private string _downstreamQueryString;
 
         public ClaimsToQueryStringForwardingTests()
         {
@@ -105,6 +107,71 @@ namespace Ocelot.AcceptanceTests
                .BDDfy();
         }
 
+        [Fact]
+        public void should_return_response_200_and_foward_claim_as_query_string_and_preserve_original_string()
+        {
+           var user = new TestUser()
+           {
+               Username = "test",
+               Password = "test",
+               SubjectId = "registered|1231231",
+               Claims = new List<Claim>
+               {
+                   new Claim("CustomerId", "123"),
+                   new Claim("LocationId", "1")
+               }
+           };
+
+           var configuration = new FileConfiguration
+           {
+               ReRoutes = new List<FileReRoute>
+                   {
+                       new FileReRoute
+                       {
+                           DownstreamPathTemplate = "/",
+                           DownstreamHostAndPorts = new List<FileHostAndPort>
+                           {
+                               new FileHostAndPort
+                               {
+                                   Host = "localhost",
+                                   Port = 57876,
+                               }
+                           },
+                           DownstreamScheme = "http",
+                           UpstreamPathTemplate = "/",
+                           UpstreamHttpMethod = new List<string> { "Get" },
+                           AuthenticationOptions = new FileAuthenticationOptions
+                           {
+                               AuthenticationProviderKey = "Test",
+                               AllowedScopes = new List<string>
+                               {
+                                   "openid", "offline_access", "api"
+                               },
+                           },
+                           AddQueriesToRequest =
+                           {
+                               {"CustomerId", "Claims[CustomerId] > value"},
+                               {"LocationId", "Claims[LocationId] > value"},
+                               {"UserType", "Claims[sub] > value[0] > |"},
+                               {"UserId", "Claims[sub] > value[1] > |"}
+                           }
+                       }
+                   }
+           };
+
+           this.Given(x => x.GivenThereIsAnIdentityServerOn("http://localhost:57888", "api", AccessTokenType.Jwt, user))
+               .And(x => x.GivenThereIsAServiceRunningOn("http://localhost:57876", 200))
+               .And(x => _steps.GivenIHaveAToken("http://localhost:57888"))
+               .And(x => _steps.GivenThereIsAConfiguration(configuration))
+               .And(x => _steps.GivenOcelotIsRunning(_options, "Test"))
+               .And(x => _steps.GivenIHaveAddedATokenToMyRequest())
+               .When(x => _steps.WhenIGetUrlOnTheApiGateway("/?test=1&test=2"))
+               .Then(x => _steps.ThenTheStatusCodeShouldBe(HttpStatusCode.OK))
+               .And(x => _steps.ThenTheResponseBodyShouldBe("CustomerId: 123 LocationId: 1 UserType: registered UserId: 1231231"))
+               .And(_ => _downstreamQueryString.ShouldBe("?test=1&test=2&CustomerId=123&LocationId=1&UserId=1231231&UserType=registered"))
+               .BDDfy();
+        }
+
         private void GivenThereIsAServiceRunningOn(string url, int statusCode)
         {
             _servicebuilder = new WebHostBuilder()
@@ -117,6 +184,8 @@ namespace Ocelot.AcceptanceTests
                 {
                     app.Run(async context =>
                     {
+                        _downstreamQueryString = context.Request.QueryString.Value;
+
                         StringValues customerId;
                         context.Request.Query.TryGetValue("CustomerId", out customerId);
 
diff --git a/test/Ocelot.UnitTests/QueryStrings/AddQueriesToRequestTests.cs b/test/Ocelot.UnitTests/QueryStrings/AddQueriesToRequestTests.cs
index d12d4294..bebe4307 100644
--- a/test/Ocelot.UnitTests/QueryStrings/AddQueriesToRequestTests.cs
+++ b/test/Ocelot.UnitTests/QueryStrings/AddQueriesToRequestTests.cs
@@ -18,7 +18,7 @@ namespace Ocelot.UnitTests.QueryStrings
     public class AddQueriesToRequestTests
     {
         private readonly AddQueriesToRequest _addQueriesToRequest;
-        private readonly HttpRequestMessage _downstreamRequest;
+        private HttpRequestMessage _downstreamRequest;
         private readonly Mock<IClaimsParser> _parser;
         private List<ClaimToThing> _configuration;
         private List<Claim> _claims;
@@ -53,6 +53,34 @@ namespace Ocelot.UnitTests.QueryStrings
                 .BDDfy();
         }
 
+        [Fact]
+        public void should_add_new_queries_to_downstream_request_and_preserve_other_queries()
+        {
+            var claims = new List<Claim>
+            {
+                new Claim("test", "data")
+            };
+
+            this.Given(
+                x => x.GivenAClaimToThing(new List<ClaimToThing>
+                {
+                    new ClaimToThing("query-key", "", "", 0)
+                }))
+                .Given(x => x.GivenClaims(claims))
+                .And(x => GivenTheDownstreamRequestHasQueryString("?test=1&test=2"))
+                .And(x => x.GivenTheClaimParserReturns(new OkResponse<string>("value")))
+                .When(x => x.WhenIAddQueriesToTheRequest())
+                .Then(x => x.ThenTheResultIsSuccess())
+                .And(x => x.ThenTheQueryIsAdded())
+                .And(x => TheTheQueryStringIs("?test=1&test=2&query-key=value"))
+                .BDDfy();
+        }
+
+        private void TheTheQueryStringIs(string expected)
+        {
+            _downstreamRequest.RequestUri.Query.ShouldBe(expected);
+        }
+
         [Fact]
         public void should_replace_existing_queries_on_downstream_request()
         {
@@ -110,6 +138,11 @@ namespace Ocelot.UnitTests.QueryStrings
             _claims = claims;
         }
 
+        private void GivenTheDownstreamRequestHasQueryString(string queryString)
+        {
+            _downstreamRequest = new HttpRequestMessage(HttpMethod.Post, $"http://my.url/abc{queryString}");
+        }
+
         private void GivenTheDownstreamRequestHasQueryString(string key, string value)
         {
             var newUri = Microsoft.AspNetCore.WebUtilities.QueryHelpers