diff --git a/src/data/CCCache.ml b/src/data/CCCache.ml
index e65b2e2f..df2f4598 100644
--- a/src/data/CCCache.ml
+++ b/src/data/CCCache.ml
@@ -269,7 +269,7 @@ module LRU(X:HASH) = struct
   let set c x y =
     let len = H.length c.table in
     assert (len <= c.size);
-    if len = c.size
+    if len = c.size || H.mem c.table x
       then replace_ c x y
       else insert_ c x y