diff --git a/CryptoExchange.Net.UnitTests/OptionsTests.cs b/CryptoExchange.Net.UnitTests/OptionsTests.cs
index 8771d90..7294c1c 100644
--- a/CryptoExchange.Net.UnitTests/OptionsTests.cs
+++ b/CryptoExchange.Net.UnitTests/OptionsTests.cs
@@ -281,7 +281,7 @@ namespace CryptoExchange.Net.UnitTests
         {
         }
 
-        public TestClientOptions(TestClientOptions? baseOn): base(baseOn)
+        public TestClientOptions(TestClientOptions baseOn): base(baseOn)
         {
             if (baseOn == null)
                 return;
diff --git a/CryptoExchange.Net/Authentication/ApiCredentials.cs b/CryptoExchange.Net/Authentication/ApiCredentials.cs
index 92e1350..3984138 100644
--- a/CryptoExchange.Net/Authentication/ApiCredentials.cs
+++ b/CryptoExchange.Net/Authentication/ApiCredentials.cs
@@ -70,7 +70,8 @@ namespace CryptoExchange.Net.Authentication
         public virtual ApiCredentials Copy()
         {
             if (PrivateKey == null)
-                return new ApiCredentials(Key!, Secret!);
+                // Use .ToString() to create a copy of the SecureString
+                return new ApiCredentials(Key!.ToString(), Secret!.ToString());
             else
                 return new ApiCredentials(PrivateKey!.Copy());
         }
diff --git a/CryptoExchange.Net/CryptoExchange.Net.csproj b/CryptoExchange.Net/CryptoExchange.Net.csproj
index d474b1f..6e4c727 100644
--- a/CryptoExchange.Net/CryptoExchange.Net.csproj
+++ b/CryptoExchange.Net/CryptoExchange.Net.csproj
@@ -6,16 +6,16 @@
     <PackageId>CryptoExchange.Net</PackageId>
     <Authors>JKorf</Authors>
     <Description>A base package for implementing cryptocurrency API's</Description>
-    <PackageVersion>5.0.0</PackageVersion>
-    <AssemblyVersion>5.0.0</AssemblyVersion>
-    <FileVersion>5.0.0</FileVersion>
+    <PackageVersion>5.1.0</PackageVersion>
+    <AssemblyVersion>5.1.0</AssemblyVersion>
+    <FileVersion>5.1.0</FileVersion>
     <PackageRequireLicenseAcceptance>false</PackageRequireLicenseAcceptance>
     <RepositoryType>git</RepositoryType>
     <RepositoryUrl>https://github.com/JKorf/CryptoExchange.Net.git</RepositoryUrl>
     <PackageProjectUrl>https://github.com/JKorf/CryptoExchange.Net</PackageProjectUrl>
     <NeutralLanguage>en</NeutralLanguage>
     <GeneratePackageOnBuild>true</GeneratePackageOnBuild>
-    <PackageReleaseNotes>See https://github.com/JKorf/CryptoExchange.Net#release-notes</PackageReleaseNotes>
+    <PackageReleaseNotes>5.1.0 - Improved dispose handling in SymbolOrderBook, Fixed TimeSync RecalculationInterval not being respected, Small rework client options</PackageReleaseNotes>
     <Nullable>enable</Nullable>
     <LangVersion>9.0</LangVersion>
     <PackageLicenseExpression>MIT</PackageLicenseExpression>
diff --git a/CryptoExchange.Net/Objects/Options.cs b/CryptoExchange.Net/Objects/Options.cs
index 16f5eb9..62eb62c 100644
--- a/CryptoExchange.Net/Objects/Options.cs
+++ b/CryptoExchange.Net/Objects/Options.cs
@@ -259,13 +259,12 @@ namespace CryptoExchange.Net.Objects
         /// ctor
         /// </summary>
         /// <param name="baseOptions">Copy values for the provided options</param>
-#pragma warning disable 8618 // Will always get filled by the provided options
+        /// <param name="newValues">Copy values for the provided options</param>
         public ApiClientOptions(ApiClientOptions baseOptions, ApiClientOptions? newValues)
         {
             BaseAddress = newValues?.BaseAddress ?? baseOptions.BaseAddress;
             ApiCredentials = newValues?.ApiCredentials?.Copy() ?? baseOptions.ApiCredentials?.Copy();
         }
-#pragma warning restore 8618
 
         /// <inheritdoc />
         public override string ToString()
@@ -318,6 +317,7 @@ namespace CryptoExchange.Net.Objects
         /// ctor
         /// </summary>
         /// <param name="baseOn">Copy values for the provided options</param>
+        /// <param name="newValues">Copy values for the provided options</param>
         public RestApiClientOptions(RestApiClientOptions baseOn, RestApiClientOptions? newValues): base(baseOn, newValues)
         {
             RateLimitingBehaviour = newValues?.RateLimitingBehaviour ?? baseOn.RateLimitingBehaviour;
diff --git a/README.md b/README.md
index 978f1f0..730e1ed 100644
--- a/README.md
+++ b/README.md
@@ -18,6 +18,11 @@ I develop and maintain this package on my own for free in my spare time. Donatio
 Alternatively, sponsor me on Github using [Github Sponsors](https://github.com/sponsors/JKorf)  
 
 ## Release notes
+* Version 5.1.0 - 24 Feb 2022
+    * Improved dispose handling in SymbolOrderBook
+    * Fixed TimeSync RecalculationInterval not being respected
+    * Small rework client options
+
 * Version 5.0.0
 	* Added Github.io page for documentation: https://jkorf.github.io/CryptoExchange.Net/
 	* Added single DateTimeConverter replacing the different timestamp converters