diff --git a/source/java/org/alfresco/repo/search/impl/solr/facet/SolrFacetService.java b/source/java/org/alfresco/repo/search/impl/solr/facet/SolrFacetService.java
index d739bf2496..d8ca7ee976 100644
--- a/source/java/org/alfresco/repo/search/impl/solr/facet/SolrFacetService.java
+++ b/source/java/org/alfresco/repo/search/impl/solr/facet/SolrFacetService.java
@@ -20,7 +20,7 @@
 package org.alfresco.repo.search.impl.solr.facet;
 
 import java.util.List;
-import java.util.Set;
+import java.util.SortedSet;
 
 import org.alfresco.repo.dictionary.Facetable;
 import org.alfresco.repo.search.impl.solr.facet.Exceptions.DuplicateFacetId;
@@ -111,7 +111,7 @@ public interface SolrFacetService
      * @return a collection of facetable {@link FacetablePropertyData}s.
      * @see Facetable
      */
-    public Set<FacetablePropertyData> getFacetableProperties();
+    public SortedSet<FacetablePropertyData> getFacetableProperties();
     
     /**
      * This method offers a convenient access point for getting all Facetable
@@ -120,7 +120,7 @@ public interface SolrFacetService
      * @return a collection of facetable {@link FacetablePropertyData}s.
      * @see Facetable
      */
-    public Set<FacetablePropertyData> getFacetableProperties(QName contentClass);
+    public SortedSet<FacetablePropertyData> getFacetableProperties(QName contentClass);
     
     /** A simple POJO/DTO intended primarily for use in an FTL model and rendering in the JSON API. */
     public static class FacetablePropertyData implements Comparable<FacetablePropertyData>
diff --git a/source/java/org/alfresco/repo/search/impl/solr/facet/SolrFacetServiceImpl.java b/source/java/org/alfresco/repo/search/impl/solr/facet/SolrFacetServiceImpl.java
index 2f1c574e7a..5ce310c440 100644
--- a/source/java/org/alfresco/repo/search/impl/solr/facet/SolrFacetServiceImpl.java
+++ b/source/java/org/alfresco/repo/search/impl/solr/facet/SolrFacetServiceImpl.java
@@ -769,9 +769,9 @@ public class SolrFacetServiceImpl extends AbstractLifecycleBean implements SolrF
         }
     }
     
-    @Override public Set<FacetablePropertyData> getFacetableProperties()
+    @Override public SortedSet<FacetablePropertyData> getFacetableProperties()
     {
-        final Set<FacetablePropertyData> result = new TreeSet<>();
+        final SortedSet<FacetablePropertyData> result = new TreeSet<>();
         
         final List<QName> allContentClasses = CollectionUtils.flatten(dictionaryService.getAllAspects(), dictionaryService.getAllTypes());
         
@@ -783,9 +783,9 @@ public class SolrFacetServiceImpl extends AbstractLifecycleBean implements SolrF
         return result;
     }
     
-    @Override public Set<FacetablePropertyData> getFacetableProperties(QName contentClass)
+    @Override public SortedSet<FacetablePropertyData> getFacetableProperties(QName contentClass)
     {
-        final Set<FacetablePropertyData> result = new TreeSet<>();
+        final SortedSet<FacetablePropertyData> result = new TreeSet<>();
         
         final Map<QName, PropertyDefinition> propertyDefs = dictionaryService.getPropertyDefs(contentClass);