diff --git a/caliGraph.py b/caliGraph.py
index ae3459e..5317418 100755
--- a/caliGraph.py
+++ b/caliGraph.py
@@ -789,11 +789,13 @@ def genScores(G, books, calcPagerank=True):
 
 def addImageToNode(node, cache, shape='circularImage'):
     name = node['label'].split(' (')[0]
-    if not name in cache:
+    if not name in cache or (cache[name]==False and random.random()<0.05):
         term = name
         img = getWikiImage(term)
         if img:
             cache[name] = img
+        else:
+            cache[name] = False
     else:
         img = cache[name]
     if img: