diff --git a/src/main/java/de/ids_mannheim/korap/query/serialize/PoliqarpPlusTree.java b/src/main/java/de/ids_mannheim/korap/query/serialize/PoliqarpPlusTree.java
index 40bd9d7..0c0d4ca 100644
--- a/src/main/java/de/ids_mannheim/korap/query/serialize/PoliqarpPlusTree.java
+++ b/src/main/java/de/ids_mannheim/korap/query/serialize/PoliqarpPlusTree.java
@@ -149,7 +149,7 @@
 
     @Override
     public void process(String query) throws QueryException {
-        ParseTree tree = null;
+        ParseTree tree;
         try {
             tree = parsePoliqarpQuery(query);
         } catch (QueryException e) {