diff --git a/src/libraries/Common/src/Interop/Windows/SspiCli/Interop.SSPI.cs b/src/libraries/Common/src/Interop/Windows/SspiCli/Interop.SSPI.cs
index 03dbb2b9346497..1051e13fc4a201 100644
--- a/src/libraries/Common/src/Interop/Windows/SspiCli/Interop.SSPI.cs
+++ b/src/libraries/Common/src/Interop/Windows/SspiCli/Interop.SSPI.cs
@@ -538,8 +538,8 @@ internal static partial SECURITY_STATUS SspiEncodeStringsAsAuthIdentity(
         [LibraryImport(Interop.Libraries.SspiCli, SetLastError = true)]
         internal static partial SECURITY_STATUS SetCredentialsAttributesW(
             in CredHandle handlePtr,
-            long ulAttribute,
+            uint ulAttribute,
             in SecPkgCred_ClientCertPolicy pBuffer,
-            long cbBuffer);
+            uint cbBuffer);
     }
 }
diff --git a/src/libraries/System.Net.Security/src/System/Net/Security/SslStreamPal.Windows.cs b/src/libraries/System.Net.Security/src/System/Net/Security/SslStreamPal.Windows.cs
index 9b570f46fed09f..2d4d75b709fd0e 100644
--- a/src/libraries/System.Net.Security/src/System/Net/Security/SslStreamPal.Windows.cs
+++ b/src/libraries/System.Net.Security/src/System/Net/Security/SslStreamPal.Windows.cs
@@ -317,9 +317,9 @@ private static unsafe void AttachCertificateStore(SafeFreeCredentials cred, X509
                 clientCertPolicy.pwszSslCtlStoreName = ptr;
                 Interop.SECURITY_STATUS errorCode = Interop.SspiCli.SetCredentialsAttributesW(
                             cred._handle,
-                            (long)Interop.SspiCli.ContextAttribute.SECPKG_ATTR_CLIENT_CERT_POLICY,
+                            (uint)Interop.SspiCli.ContextAttribute.SECPKG_ATTR_CLIENT_CERT_POLICY,
                             clientCertPolicy,
-                            sizeof(Interop.SspiCli.SecPkgCred_ClientCertPolicy));
+                            (uint)sizeof(Interop.SspiCli.SecPkgCred_ClientCertPolicy));
 
                 if (errorCode != Interop.SECURITY_STATUS.OK)
                 {