diff --git a/src/main/java/de/ids_mannheim/korap/KrillCollection.java b/src/main/java/de/ids_mannheim/korap/KrillCollection.java
index d839422..d49c4d6 100644
--- a/src/main/java/de/ids_mannheim/korap/KrillCollection.java
+++ b/src/main/java/de/ids_mannheim/korap/KrillCollection.java
@@ -8,7 +8,6 @@
 import de.ids_mannheim.korap.util.QueryException;
 import de.ids_mannheim.korap.response.Result;
 
-import org.apache.lucene.search.spans.SpanQuery;
 import org.apache.lucene.search.*;
 import org.apache.lucene.index.*;
 import org.apache.lucene.util.BytesRef;
diff --git a/src/main/java/de/ids_mannheim/korap/query/wrap/SpanQueryWrapper.java b/src/main/java/de/ids_mannheim/korap/query/wrap/SpanQueryWrapper.java
index 0855885..82349b2 100644
--- a/src/main/java/de/ids_mannheim/korap/query/wrap/SpanQueryWrapper.java
+++ b/src/main/java/de/ids_mannheim/korap/query/wrap/SpanQueryWrapper.java
@@ -7,6 +7,7 @@
 import de.ids_mannheim.korap.query.SpanWithinQuery;
 
 // TODO: Add warnings and errors - using KrillQuery
+// TODO: Rename isEmpty to isAny!
 
 /**
  * A wrapper base class for Lucene SpanQueries,
@@ -98,7 +99,7 @@
     /**
      * Boolean value indicating that the wrapped query is
      * <tt>null</tt>, meaning it doesn't match anything at
-     * all.
+     * all (i.e. a zero-width assertion).
      * 
      * For example the segment denoting an adjective
      * in the following Poliqarp expression doen't match