diff --git a/src/main/java/org/elasticsearch/common/lucene/docset/DocSets.java b/src/main/java/org/elasticsearch/common/lucene/docset/DocSets.java
index 3bb3edb94e3..5ed4385aa26 100644
--- a/src/main/java/org/elasticsearch/common/lucene/docset/DocSets.java
+++ b/src/main/java/org/elasticsearch/common/lucene/docset/DocSets.java
@@ -24,6 +24,7 @@ import org.apache.lucene.search.DocIdSet;
 import org.apache.lucene.search.DocIdSetIterator;
 import org.apache.lucene.util.FixedBitSet;
 import org.apache.lucene.util.OpenBitSet;
+import org.elasticsearch.common.Nullable;
 
 import java.io.IOException;
 
@@ -116,22 +117,40 @@ public class DocSets {
     /**
      * Returns a cacheable version of the doc id set (might be the same instance provided as a parameter).
      */
-    public static DocSet cacheable(IndexReader reader, DocIdSet docIdSet) throws IOException {
-        if (docIdSet == null) {
+    public static DocSet cacheable(IndexReader reader, @Nullable DocIdSet set) throws IOException {
+        if (set == null) {
             return DocSet.EMPTY_DOC_SET;
-        } else if (docIdSet.isCacheable() && (docIdSet instanceof DocSet)) {
-            return (DocSet) docIdSet;
-        } else if (docIdSet instanceof FixedBitSet) {
-            return new FixedBitDocSet((FixedBitSet) docIdSet);
-        } else if (docIdSet instanceof OpenBitSet) {
-            return new OpenBitDocSet((OpenBitSet) docIdSet);
-        } else {
-            final DocIdSetIterator it = docIdSet.iterator();
-            // null is allowed to be returned by iterator(),
-            // in this case we wrap with the empty set,
-            // which is cacheable.
-            return (it == null) ? DocSet.EMPTY_DOC_SET : new FixedBitDocSet(createFixedBitSet(it, reader.maxDoc()));
         }
+        if (set == DocIdSet.EMPTY_DOCIDSET) {
+            return DocSet.EMPTY_DOC_SET;
+        }
+
+        DocIdSetIterator it = set.iterator();
+        if (it == null) {
+            return DocSet.EMPTY_DOC_SET;
+        }
+        int doc = it.nextDoc();
+        if (doc == DocIdSetIterator.NO_MORE_DOCS) {
+            return DocSet.EMPTY_DOC_SET;
+        }
+
+        if (set.isCacheable() && (set instanceof DocSet)) {
+            return (DocSet) set;
+        }
+        if (set instanceof FixedBitSet) {
+            return new FixedBitDocSet((FixedBitSet) set);
+        }
+        if (set instanceof OpenBitSet) {
+            return new OpenBitDocSet((OpenBitSet) set);
+        }
+
+        // work with the iterator...
+        FixedBitSet fixedBitSet = new FixedBitSet(reader.maxDoc());
+        fixedBitSet.set(doc);
+        while ((doc = it.nextDoc()) != DocIdSetIterator.NO_MORE_DOCS) {
+            fixedBitSet.set(doc);
+        }
+        return new FixedBitDocSet(fixedBitSet);
     }
 
     private DocSets() {
diff --git a/src/main/java/org/elasticsearch/index/cache/filter/support/FilterCacheValue.java b/src/main/java/org/elasticsearch/index/cache/filter/support/FilterCacheValue.java
index 5593b2b2d06..87f5579eb94 100644
--- a/src/main/java/org/elasticsearch/index/cache/filter/support/FilterCacheValue.java
+++ b/src/main/java/org/elasticsearch/index/cache/filter/support/FilterCacheValue.java
@@ -19,14 +19,6 @@
 
 package org.elasticsearch.index.cache.filter.support;
 
-import org.apache.lucene.index.IndexReader;
-import org.apache.lucene.search.DocIdSet;
-import org.apache.lucene.search.DocIdSetIterator;
-import org.elasticsearch.common.lucene.docset.DocSet;
-import org.elasticsearch.common.lucene.docset.DocSets;
-
-import java.io.IOException;
-
 public class FilterCacheValue<T> {
 
     private final T value;
@@ -38,24 +30,4 @@ public class FilterCacheValue<T> {
     public T value() {
         return value;
     }
-
-
-    public static DocSet cacheable(IndexReader reader, DocIdSet set) throws IOException {
-        if (set == null) {
-            return DocSet.EMPTY_DOC_SET;
-        }
-        if (set == DocIdSet.EMPTY_DOCIDSET) {
-            return DocSet.EMPTY_DOC_SET;
-        }
-
-        DocIdSetIterator it = set.iterator();
-        if (it == null) {
-            return DocSet.EMPTY_DOC_SET;
-        }
-        int doc = it.nextDoc();
-        if (doc == DocIdSetIterator.NO_MORE_DOCS) {
-            return DocSet.EMPTY_DOC_SET;
-        }
-        return DocSets.cacheable(reader, set);
-    }
 }
\ No newline at end of file
diff --git a/src/main/java/org/elasticsearch/index/cache/filter/weighted/WeightedFilterCache.java b/src/main/java/org/elasticsearch/index/cache/filter/weighted/WeightedFilterCache.java
index 5f68be5a840..16a89cb3003 100644
--- a/src/main/java/org/elasticsearch/index/cache/filter/weighted/WeightedFilterCache.java
+++ b/src/main/java/org/elasticsearch/index/cache/filter/weighted/WeightedFilterCache.java
@@ -30,6 +30,7 @@ import org.apache.lucene.search.Filter;
 import org.elasticsearch.ElasticSearchException;
 import org.elasticsearch.common.inject.Inject;
 import org.elasticsearch.common.lucene.docset.DocSet;
+import org.elasticsearch.common.lucene.docset.DocSets;
 import org.elasticsearch.common.lucene.search.NoCacheFilter;
 import org.elasticsearch.common.metrics.CounterMetric;
 import org.elasticsearch.common.metrics.MeanMetric;
@@ -173,7 +174,7 @@ public class WeightedFilterCache extends AbstractIndexComponent implements Filte
                 }
 
                 DocIdSet docIdSet = filter.getDocIdSet(reader);
-                DocSet docSet = FilterCacheValue.cacheable(reader, docIdSet);
+                DocSet docSet = DocSets.cacheable(reader, docIdSet);
                 cacheValue = new FilterCacheValue<DocSet>(docSet);
                 // we might put the same one concurrently, that's fine, it will be replaced and the removal
                 // will be called