diff --git a/CryptoExchange.Net/Authentication/ApiCredentials.cs b/CryptoExchange.Net/Authentication/ApiCredentials.cs
index 3984138..c3e4523 100644
--- a/CryptoExchange.Net/Authentication/ApiCredentials.cs
+++ b/CryptoExchange.Net/Authentication/ApiCredentials.cs
@@ -70,8 +70,8 @@ namespace CryptoExchange.Net.Authentication
         public virtual ApiCredentials Copy()
         {
             if (PrivateKey == null)
-                // Use .ToString() to create a copy of the SecureString
-                return new ApiCredentials(Key!.ToString(), Secret!.ToString());
+                // Use .GetString() to create a copy of the SecureString
+                return new ApiCredentials(Key!.GetString(), Secret!.GetString());
             else
                 return new ApiCredentials(PrivateKey!.Copy());
         }
diff --git a/CryptoExchange.Net/CryptoExchange.Net.csproj b/CryptoExchange.Net/CryptoExchange.Net.csproj
index 6e4c727..4b4663b 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>5.1.0</PackageVersion>
-    <AssemblyVersion>5.1.0</AssemblyVersion>
-    <FileVersion>5.1.0</FileVersion>
+    <PackageVersion>5.1.1</PackageVersion>
+    <AssemblyVersion>5.1.1</AssemblyVersion>
+    <FileVersion>5.1.1</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>5.1.0 - Improved dispose handling in SymbolOrderBook, Fixed TimeSync RecalculationInterval not being respected, Small rework client options</PackageReleaseNotes>
+    <PackageReleaseNotes>5.1.1 - Fixed issue ApiCredentials</PackageReleaseNotes>
     <Nullable>enable</Nullable>
     <LangVersion>9.0</LangVersion>
     <PackageLicenseExpression>MIT</PackageLicenseExpression>
diff --git a/README.md b/README.md
index 730e1ed..3eab330 100644
--- a/README.md
+++ b/README.md
@@ -18,6 +18,9 @@ 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 5.1.1 - 24 Feb 2022
+    * Fixed issue ApiCredentials
+
 * Version 5.1.0 - 24 Feb 2022
     * Improved dispose handling in SymbolOrderBook
     * Fixed TimeSync RecalculationInterval not being respected