diff --git a/Intacct.SDK/Xml/Request/OperationBlock.cs b/Intacct.SDK/Xml/Request/OperationBlock.cs
index 83dd91a1..8ab20a18 100644
--- a/Intacct.SDK/Xml/Request/OperationBlock.cs
+++ b/Intacct.SDK/Xml/Request/OperationBlock.cs
@@ -44,7 +44,7 @@ public OperationBlock(ClientConfig clientConfig, RequestConfig requestConfig, Li
             else if (credentials != null && credentials.GetType() == typeof(LoginCredentials))
             {
                 LoginCredentials loginCreds = credentials as LoginCredentials;
-                this.Authentication = new LoginAuthentication(loginCreds.UserId, loginCreds.CompanyId, loginCreds.Password, loginCreds.EntityId);
+                this.Authentication = new LoginAuthentication(loginCreds.UserId, loginCreds.CompanyId, loginCreds.Password, loginCreds.EntityId ?? clientConfig.EntityId);
             }
             else if (!string.IsNullOrEmpty(clientConfig.SessionId))
             {