diff --git a/Minio/Credentials/CertificateIdentityProvider.cs b/Minio/Credentials/CertificateIdentityProvider.cs
index d6f914e0..6dae299a 100644
--- a/Minio/Credentials/CertificateIdentityProvider.cs
+++ b/Minio/Credentials/CertificateIdentityProvider.cs
@@ -15,8 +15,8 @@
  * limitations under the License.
  */
 
+
 using System.Globalization;
-using System.Security.Authentication;
 using System.Security.Cryptography.X509Certificates;
 using System.Text;
 using System.Web;
@@ -24,6 +24,11 @@
 using Minio.DataModel;
 using Minio.Exceptions;
 using Minio.Helper;
+#if (NET472_OR_GREATER || NET6_0_OR_GREATER)
+using System.Security.Authentication;
+#else
+using System.Net;
+#endif
 
 /*
  * Certificate Identity Credential provider.
@@ -72,8 +77,7 @@ public async ValueTask<AccessCredentials> GetCredentialsAsync()
         {
             var content = await response.Content.ReadAsStringAsync().ConfigureAwait(false);
             using var stream = Encoding.UTF8.GetBytes(content).AsMemory().AsStream();
-            certResponse =
-                Utils.DeserializeXml<CertificateResponse>(stream);
+            certResponse = Utils.DeserializeXml<CertificateResponse>(stream);
         }
 
         if (Credentials is null && certResponse?.Cr is not null)
@@ -118,10 +122,12 @@ public CertificateIdentityProvider Build()
         builder.Query = query.ToString();
         PostEndpoint = builder.Uri;
 
-        var handler = new HttpClientHandler
-        {
-            ClientCertificateOptions = ClientCertificateOption.Manual, SslProtocols = SslProtocols.Tls12
-        };
+        var handler = new HttpClientHandler { ClientCertificateOptions = ClientCertificateOption.Manual };
+#if (NET472_OR_GREATER || NET6_0_OR_GREATER)
+        handler.SslProtocols = SslProtocols.Tls12;
+#else
+        ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12 | SecurityProtocolType.Tls11;
+#endif
         _ = handler.ClientCertificates.Add(ClientCertificate);
         HttpClient ??= new HttpClient(handler) { BaseAddress = new Uri(StsEndpoint) };