diff --git a/extensions/wikidata/src/org/openrefine/wikidata/utils/EntityCache.java b/extensions/wikidata/src/org/openrefine/wikidata/utils/EntityCache.java
index b27a4abf1..360183470 100644
--- a/extensions/wikidata/src/org/openrefine/wikidata/utils/EntityCache.java
+++ b/extensions/wikidata/src/org/openrefine/wikidata/utils/EntityCache.java
@@ -7,6 +7,7 @@ import org.wikidata.wdtk.datamodel.interfaces.EntityDocument;
 import org.wikidata.wdtk.datamodel.interfaces.EntityIdValue;
 import org.wikidata.wdtk.wikibaseapi.ApiConnection;
 import org.wikidata.wdtk.wikibaseapi.WikibaseDataFetcher;
+import org.wikidata.wdtk.wikibaseapi.apierrors.MediaWikiApiErrorException;
 
 import com.google.common.cache.CacheBuilder;
 import com.google.common.cache.CacheLoader;
@@ -15,27 +16,42 @@ import com.google.common.cache.LoadingCache;
 public class EntityCache {
     private static EntityCache _entityCache = new EntityCache();
     
-    private LoadingCache<EntityIdValue, EntityDocument> _cache;
+    private LoadingCache<String, EntityDocument> _cache = null;
     private WikibaseDataFetcher _fetcher;
     
-    
     private EntityCache() {
         ApiConnection connection = ApiConnection.getWikidataApiConnection();
         _fetcher = new WikibaseDataFetcher(connection, Datamodel.SITE_WIKIDATA);
 
+        System.out.println("Creating fresh cache");
         _cache = CacheBuilder.newBuilder()
                 .maximumSize(4096)
                 .expireAfterWrite(1, TimeUnit.HOURS)
                 .build(
-             new CacheLoader<EntityIdValue, EntityDocument>() {
-                 public EntityDocument load(EntityIdValue entityId) throws Exception {
-                     EntityDocument doc = _fetcher.getEntityDocument(entityId.getId());
-                     return doc;
+             new CacheLoader<String, EntityDocument>() {
+                 public EntityDocument load(String entityId) throws Exception {
+                     EntityDocument doc = _fetcher.getEntityDocument(entityId);
+                     if (doc != null) {
+                         return doc;
+                     } else {
+                         throw new MediaWikiApiErrorException("400", "Unknown entity id \""+entityId+"\"");
+                     }
                  }
              });
     }
     
-    public static EntityDocument getEntityDocument(EntityIdValue qid) {
-        return _entityCache._cache.apply(qid);
+    public EntityDocument get(EntityIdValue id) {
+        return _cache.apply(id.getId());
+    }
+    
+    public static EntityCache getEntityCache() {
+        if (_entityCache == null) {
+            _entityCache = new EntityCache();
+        }
+        return _entityCache;
+    }
+    
+    public static EntityDocument getEntityDocument(EntityIdValue id) {
+        return getEntityCache().get(id);
     }
 }