diff --git a/src/api/transactions.rs b/src/api/transactions.rs
index 702a4f9..2747f92 100644
--- a/src/api/transactions.rs
+++ b/src/api/transactions.rs
@@ -132,7 +132,8 @@ pub enum AccountTarget {
 #[cfg_attr(feature = "schemas", derive(schemars::JsonSchema))]
 #[cfg_attr(feature = "schemas", serde(untagged))]
 pub enum UnvalidatedAccountTarget {
-    Interop(#[garde(pattern("^thc:.+$"))] String),
+    /// Interop user
+    Interop(#[garde(pattern("^.{2,}@[a-z0-9]{2,4}$"))] String),
     Selector(#[garde(dive)] UnvalidatedAccountSelector),
 }
 
@@ -150,7 +151,7 @@ impl<'de> Deserialize<'de> for UnvalidatedAccountTarget {
         Ok(match AccountTargetHelper::deserialize(deserializer)? {
             AccountTargetHelper::Text(text) => {
                 // TODO: don't hardcode prefix
-                if let Some(text) = text.strip_prefix("thc:") {
+                if let Some(text) = text.strip_suffix("@thc") {
                     Self::Interop(text.into())
                 } else {
                     Self::Selector(UnvalidatedAccountSelector::Username(Name(text)))