diff --git a/token-core/tcx-proto/src/params.proto b/token-core/tcx-proto/src/params.proto
index caaed7e3..b64d0e95 100644
--- a/token-core/tcx-proto/src/params.proto
+++ b/token-core/tcx-proto/src/params.proto
@@ -262,7 +262,7 @@ message MigrateKeystoreParam {
     string id = 1;
     string name = 2;
     string source = 3;
-    int64 createdAt = 4;
+    string createdAt = 4;
     repeated AccountResponse accounts = 5;
 }
 
diff --git a/token-core/tcx/src/api.rs b/token-core/tcx/src/api.rs
index 1778b672..40f09dae 100644
--- a/token-core/tcx/src/api.rs
+++ b/token-core/tcx/src/api.rs
@@ -677,8 +677,8 @@ pub struct LegacyKeystoreResult {
     pub name: ::prost::alloc::string::String,
     #[prost(string, tag = "3")]
     pub source: ::prost::alloc::string::String,
-    #[prost(int64, tag = "4")]
-    pub created_at: i64,
+    #[prost(string, tag = "4")]
+    pub created_at: ::prost::alloc::string::String,
     #[prost(message, repeated, tag = "5")]
     pub accounts: ::prost::alloc::vec::Vec<AccountResponse>,
 }
diff --git a/token-core/tcx/src/migration.rs b/token-core/tcx/src/migration.rs
index b80872d2..c762f065 100644
--- a/token-core/tcx/src/migration.rs
+++ b/token-core/tcx/src/migration.rs
@@ -326,7 +326,7 @@ fn parse_legacy_kesytore(contents: String) -> Result<LegacyKeystoreResult> {
         id: legacy_keystore.id.to_string(),
         name: meta.name.to_string(),
         source: meta.source.as_ref().unwrap_or(&"".to_string()).to_string(),
-        created_at,
+        created_at: created_at.to_string(),
         accounts: vec![account],
     };
     Ok(keystore_result)
@@ -379,7 +379,7 @@ fn parse_tcx_keystore(v: &Value) -> Result<LegacyKeystoreResult> {
         id,
         name: meta.name.to_string(),
         source: meta.source.to_string(),
-        created_at: meta.timestamp,
+        created_at: meta.timestamp.to_string(),
         accounts: account_responses,
     };
     Ok(keystore_result)