diff --git a/proto/environments/environments_v1.proto b/proto/environments/environments_v1.proto
index 750adf7..1f7a3f5 100644
--- a/proto/environments/environments_v1.proto
+++ b/proto/environments/environments_v1.proto
@@ -62,6 +62,7 @@ message GetOptions {
 
 message ListOptions {
   EnvironmentMetadata metadata = 1;
+  string search_string = 2;
   OwnerId owner_id = 3;
   Token token = 4;
 }