diff --git a/src/types/user.ts b/src/types/user.ts
index b49d9d5..7f6c8eb 100644
--- a/src/types/user.ts
+++ b/src/types/user.ts
@@ -88,6 +88,11 @@ export type ExperimentUser = {
    */
   library?: string;
 
+  /**
+   * Predefined field, can be manually provided
+   */
+  ip_address?: string;
+
   /**
    * Custom user properties
    */