diff --git a/include/import/lru.h b/include/import/lru.h
index 2b8ac4a01..f922449b2 100644
--- a/include/import/lru.h
+++ b/include/import/lru.h
@@ -63,9 +63,10 @@ struct lru64 {
 	void *domain;                 /* who this data belongs to */
 	unsigned long long revision;  /* data revision (to avoid use-after-free) */
 	void *data;                   /* returned value, user decides how to use this */
+	void (*free)(void *data);     /* function to release data, if needed */
 };
 
 struct lru64 *lru64_get(unsigned long long key, struct lru64_head *lru, void *domain, unsigned long long revision);
-void lru64_commit(struct lru64 *elem, void *data, void *domain, unsigned long long revision);
+void lru64_commit(struct lru64 *elem, void *data, void *domain, unsigned long long revision, void (*free)(void *));
 struct lru64_head *lru64_new(int size);
 int lru64_destroy(struct lru64_head *lru);
diff --git a/src/lru.c b/src/lru.c
index bdb525d11..1b997d8b8 100644
--- a/src/lru.c
+++ b/src/lru.c
@@ -94,8 +94,11 @@ struct lru64 *lru64_get(unsigned long long key, struct lru64_head *lru,
 			__eb64_delete(&old->node);
 			if (!lru->spare)
 				lru->spare = old;
-			else
+			else {
+				if (old->data && old->free);
+					old->free(old->data);
 				free(old);
+			}
 			lru->cache_usage--;
 		}
 	}
@@ -107,7 +110,8 @@ struct lru64 *lru64_get(unsigned long long key, struct lru64_head *lru,
  * with the result from a call to lru64_get(). The caller might lock it using a
  * spinlock or mutex shared with the one around lru64_get().
  */
-void lru64_commit(struct lru64 *elem, void *data, void *domain, unsigned long long revision)
+void lru64_commit(struct lru64 *elem, void *data, void *domain,
+		  unsigned long long revision, void (*free)(void *))
 {
 	if (!elem)
 		return;
@@ -115,6 +119,7 @@ void lru64_commit(struct lru64 *elem, void *data, void *domain, unsigned long lo
 	elem->data = data;
 	elem->revision = revision;
 	elem->domain = domain;
+	elem->free = free;
 }
 
 /* Create a new LRU cache of <size> entries. Returns the new cache or NULL in
@@ -152,6 +157,8 @@ int lru64_destroy(struct lru64_head *lru)
 			/* not locked */
 			LIST_DEL(&elem->lru);
 			eb64_delete(&elem->node);
+			if (elem->data && elem->free);
+				elem->free(elem->data);
 			free(elem);
 			lru->cache_usage--;
 			lru->cache_size--;
diff --git a/src/pattern.c b/src/pattern.c
index 656c19065..9626c6537 100644
--- a/src/pattern.c
+++ b/src/pattern.c
@@ -499,7 +499,7 @@ struct pattern *pat_match_str(struct sample *smp, struct pattern_expr *expr, int
 	}
 
 	if (lru)
-		lru64_commit(lru, ret, expr, expr->revision);
+	    lru64_commit(lru, ret, expr, expr->revision, NULL);
 
 	return ret;
 }
@@ -534,7 +534,7 @@ struct pattern *pat_match_bin(struct sample *smp, struct pattern_expr *expr, int
 	}
 
 	if (lru)
-		lru64_commit(lru, ret, expr, expr->revision);
+	    lru64_commit(lru, ret, expr, expr->revision, NULL);
 
 	return ret;
 }
@@ -568,7 +568,7 @@ struct pattern *pat_match_reg(struct sample *smp, struct pattern_expr *expr, int
 	}
 
 	if (lru)
-		lru64_commit(lru, ret, expr, expr->revision);
+	    lru64_commit(lru, ret, expr, expr->revision, NULL);
 
 	return ret;
 }
@@ -634,7 +634,7 @@ struct pattern *pat_match_beg(struct sample *smp, struct pattern_expr *expr, int
 	}
 
 	if (lru)
-		lru64_commit(lru, ret, expr, expr->revision);
+	    lru64_commit(lru, ret, expr, expr->revision, NULL);
 
 	return ret;
 }
@@ -673,7 +673,7 @@ struct pattern *pat_match_end(struct sample *smp, struct pattern_expr *expr, int
 	}
 
 	if (lru)
-		lru64_commit(lru, ret, expr, expr->revision);
+	    lru64_commit(lru, ret, expr, expr->revision, NULL);
 
 	return ret;
 }
@@ -730,7 +730,7 @@ struct pattern *pat_match_sub(struct sample *smp, struct pattern_expr *expr, int
 	}
  leave:
 	if (lru)
-		lru64_commit(lru, ret, expr, expr->revision);
+	    lru64_commit(lru, ret, expr, expr->revision, NULL);
 
 	return ret;
 }