diff --git a/modules/experimental/cache_pqueue.c b/modules/experimental/cache_pqueue.c
index 0b458b79c6..610f426c86 100644
--- a/modules/experimental/cache_pqueue.c
+++ b/modules/experimental/cache_pqueue.c
@@ -336,3 +336,19 @@ void cache_pq_print(cache_pqueue_t *q,
     }
     cache_pq_free(dup);
 }
+
+static int cache_pq_subtree_is_valid(cache_pqueue_t *q, int pos)
+{
+    if ((left(pos) <q->size &&(q->pri(q->d[pos]) < q->pri(q->d[left(pos)]))) ||
+        (right(pos)<q->size &&(q->pri(q->d[pos]) < q->pri(q->d[right(pos)]))))
+    {
+        return 0;
+    }
+    return ((left(pos)>=q->size ||(cache_pq_subtree_is_valid(q, left(pos)))) &&
+            (right(pos)>=q->size||(cache_pq_subtree_is_valid(q, right(pos)))));
+}
+
+int cache_pq_is_valid(cache_pqueue_t *q)
+{
+    return cache_pq_subtree_is_valid(q, 1);
+}
diff --git a/modules/experimental/cache_pqueue.h b/modules/experimental/cache_pqueue.h
index a650f44dac..f3efea4878 100644
--- a/modules/experimental/cache_pqueue.h
+++ b/modules/experimental/cache_pqueue.h
@@ -187,6 +187,14 @@ void cache_pq_dump(cache_pqueue_t *q,
                    FILE *out,
                    cache_pqueue_print_entry print);
 
+/**
+ * checks that the pq is in the right order, etc
+ * @internal
+ * debug function only
+ * @param q the queue
+ */
+int cache_pq_is_valid(cache_pqueue_t *q);
+
 #ifdef __cplusplus
 }
 #endif