diff --git a/src/services/member/service.rs b/src/services/member/service.rs
index 084134c..f53eff6 100644
--- a/src/services/member/service.rs
+++ b/src/services/member/service.rs
@@ -207,7 +207,18 @@ impl Service<'_> {
           })
         })?;
 
-        let parent_member_id = match request.referrer_member_username {
+        let referrer_member_username = match &request.referrer_member_username {
+          Some(d) => {
+            if d.trim().is_empty() {
+              None
+            } else {
+              Some(d.clone())
+            }
+          },
+          None => None,
+        };
+
+        let parent_member_id = match referrer_member_username {
           Some(referrer_member_username) => {
             match self
               .member_repository