diff --git a/src/main/java/de/ids_mannheim/korap/KorapQuery.java b/src/main/java/de/ids_mannheim/korap/KorapQuery.java
index 1485f5d..b0ed21e 100644
--- a/src/main/java/de/ids_mannheim/korap/KorapQuery.java
+++ b/src/main/java/de/ids_mannheim/korap/KorapQuery.java
@@ -291,8 +291,8 @@
 	    throw new QueryException("Unknown group operation");
 
 	case "korap:reference":
-	    if (json.has("operation") && json.get("operation").asText() != "operation:focus")
-		throw new QueryException("Reference operation not supported yet");
+	    if (json.has("operation") && !json.get("operation").asText().equals("operation:focus"))
+		throw new QueryException("Reference operation " + json.get("operation").asText() + " not supported yet");
 
 	    int number = 0;
 
diff --git a/todo.txt b/todo.txt
deleted file mode 100644
index 15a91a4..0000000
--- a/todo.txt
+++ /dev/null
@@ -1,2 +0,0 @@
-- Fix ALL @ignored tests!
-- optimize matchmodifyclassspans