diff --git a/crates/service/web/storyteller_web/src/http_server/endpoints/users/create_account_handler.rs b/crates/service/web/storyteller_web/src/http_server/endpoints/users/create_account_handler.rs
index 1d7701c7fe..0046a129c5 100644
--- a/crates/service/web/storyteller_web/src/http_server/endpoints/users/create_account_handler.rs
+++ b/crates/service/web/storyteller_web/src/http_server/endpoints/users/create_account_handler.rs
@@ -229,7 +229,7 @@ pub async fn create_account_handler(
       maybe_source,
       maybe_referral_url,
       maybe_landing_url,
-      maybe_referral_partner: sanitize_referral_username(request.maybe_referral_username.as_deref()),
+      maybe_referral_partner: request.maybe_referral_username.as_deref().and_then(sanitize_referral_username),
       maybe_user_token: None, // NB: This parameter is for internal testing only
     }
   ).await;
diff --git a/crates/service/web/storyteller_web/src/http_server/endpoints/users/google_sso/google_sso_handler.rs b/crates/service/web/storyteller_web/src/http_server/endpoints/users/google_sso/google_sso_handler.rs
index 7fdbfca7aa..3cf5b5bd17 100644
--- a/crates/service/web/storyteller_web/src/http_server/endpoints/users/google_sso/google_sso_handler.rs
+++ b/crates/service/web/storyteller_web/src/http_server/endpoints/users/google_sso/google_sso_handler.rs
@@ -243,7 +243,7 @@ pub async fn google_sso_handler(
         claims_subject: &claims_subject,
         claims_email_address: &claims_email_address,
         mysql_connection: &mut mysql_connection,
-        maybe_referral_partner: sanitize_referral_username(request.maybe_referral_username.as_deref()),
+        maybe_referral_partner: request.maybe_referral_username.as_deref().and_then(sanitize_referral_username),
       }).await?;
 
       user_token = result.user_token;
diff --git a/crates/service/web/storyteller_web/src/util/cleaners/sanitize_referral_username.rs b/crates/service/web/storyteller_web/src/util/cleaners/sanitize_referral_username.rs
index c612608005..a60b370df9 100644
--- a/crates/service/web/storyteller_web/src/util/cleaners/sanitize_referral_username.rs
+++ b/crates/service/web/storyteller_web/src/util/cleaners/sanitize_referral_username.rs
@@ -1,10 +1,10 @@
 const MAX_REFERRAL_PARTNER_LENGTH: usize = 32;
 
-/// Sanitize an optional referral username/code for storage.
+/// Sanitize a referral username/code for storage
+/// in the `users.maybe_referral_partner` column.
 /// Trims whitespace and truncates to 32 characters.
-/// Returns None if the input is None or empty after trimming.
-pub fn sanitize_referral_username(maybe_value: Option<&str>) -> Option<String> {
-  let value = maybe_value?;
+/// Returns None if empty after trimming.
+pub fn sanitize_referral_username(value: &str) -> Option<String> {
   let trimmed = value.trim();
   if trimmed.is_empty() {
     return None;
@@ -17,35 +17,30 @@ pub fn sanitize_referral_username(maybe_value: Option<&str>) -> Option<String> {
 mod tests {
   use super::*;
 
-  #[test]
-  fn none_returns_none() {
-    assert_eq!(sanitize_referral_username(None), None);
-  }
-
   #[test]
   fn empty_returns_none() {
-    assert_eq!(sanitize_referral_username(Some("")), None);
+    assert_eq!(sanitize_referral_username(""), None);
   }
 
   #[test]
   fn whitespace_only_returns_none() {
-    assert_eq!(sanitize_referral_username(Some("   ")), None);
+    assert_eq!(sanitize_referral_username("   "), None);
   }
 
   #[test]
   fn trims_whitespace() {
-    assert_eq!(sanitize_referral_username(Some("  alice  ")), Some("alice".to_string()));
+    assert_eq!(sanitize_referral_username("  alice  "), Some("alice".to_string()));
   }
 
   #[test]
   fn truncates_long_values() {
     let long = "a".repeat(50);
-    let result = sanitize_referral_username(Some(&long)).unwrap();
+    let result = sanitize_referral_username(&long).unwrap();
     assert_eq!(result.len(), 32);
   }
 
   #[test]
   fn passes_through_normal_values() {
-    assert_eq!(sanitize_referral_username(Some("bob123")), Some("bob123".to_string()));
+    assert_eq!(sanitize_referral_username("bob123"), Some("bob123".to_string()));
   }
 }