diff --git a/src/main/java/de/ids_mannheim/korap/query/serialize/CollectionQuery.java b/src/main/java/de/ids_mannheim/korap/query/serialize/CollectionQuery.java
index cb04f90..5cdd28c 100644
--- a/src/main/java/de/ids_mannheim/korap/query/serialize/CollectionQuery.java
+++ b/src/main/java/de/ids_mannheim/korap/query/serialize/CollectionQuery.java
@@ -7,6 +7,7 @@
 import com.fasterxml.jackson.databind.ObjectMapper;
 import com.google.common.collect.ArrayListMultimap;
 import com.google.common.collect.Multimap;
+import com.google.common.collect.Multiset;
 
 import java.io.IOException;
 import java.util.*;
@@ -101,14 +102,17 @@
     }
 
     // fixme: map can only have one key/value pair. thus,
-    // text class can only be added once. Multiple types are not possible!
+    // fixme: text class can only be added once. Multiple types are not possible!
     public CollectionQuery addMetaFilter(String queries) {
         Multimap<String, String> m = resEq(queries);
         boolean multypes = m.keys().size() > 1;
         String def_key = null;
 
-        if (!multypes)
-            def_key = m.keys().toArray(new String[0])[0];
+
+        if (!multypes){
+            Multiset<String> keys = m.keys();
+            def_key = keys.toArray(new String[keys.size()])[0];
+        }
 
         List value = this.createValue(m);
         // todo: missing: - takes only one resource, but resources can be chained!
diff --git a/src/main/java/de/ids_mannheim/korap/query/serialize/QuerySerializer.java b/src/main/java/de/ids_mannheim/korap/query/serialize/QuerySerializer.java
index e6ffbe6..6e8fb62 100644
--- a/src/main/java/de/ids_mannheim/korap/query/serialize/QuerySerializer.java
+++ b/src/main/java/de/ids_mannheim/korap/query/serialize/QuerySerializer.java
@@ -105,13 +105,11 @@
      * @param outFile       The file to which the serialization is written
      * @param query         The query string
      * @param queryLanguage The query language. As of 13/11/20, this must be either 'poliqarp' or 'poliqarpplus'. Some extra maven stuff needs to done to support CosmasII ('cosmas') [that maven stuff would be to tell maven how to build the cosmas grammar and where to find the classes]
-     * @throws JsonGenerationException
-     * @throws JsonMappingException
      * @throws IOException
      * @throws QueryException
      */
     public void run(String query, String queryLanguage, String outFile)
-            throws JsonGenerationException, JsonMappingException, IOException, QueryException {
+            throws IOException, QueryException {
         if (queryLanguage.equals("poliqarp")) {
             ast = new PoliqarpPlusTree(query);
         } else if (queryLanguage.toLowerCase().equals("cosmas2")) {
@@ -125,7 +123,7 @@
         mapper.writeValue(new File(outFile), requestMap);
     }
 
-    public String buildQuery(String query, String ql, List<String> parents,
+    public String buildQuery(String query, String ql, String collection,
                              String cli, String cri, int cls, int crs,
                              int num, int page, boolean cutoff)
             throws QueryException {
@@ -146,8 +144,6 @@
         }
 
         Map<String, Object> requestMap = ast.getRequestMap();
-        CollectionQuery collectionQuery = new CollectionQuery();
-        collectionQuery.addResources(parents);
 
         MetaQuery meta = new MetaQuery();
         meta.addContext(cls, cli, crs, cri);
@@ -155,19 +151,12 @@
         meta.addEntry("startPage", page);
         meta.addEntry("count", num);
 
-        try
-
-        {
-            requestMap.put("collections", collectionQuery.raw());
+        try {
+            requestMap.put("collections", collection);
             requestMap.put("meta", meta.raw());
             return mapper.writeValueAsString(requestMap);
-        } catch (
-                IOException e
-                )
-
-        {
+        } catch (IOException e){
             return "";
         }
-
     }
 }