diff --git a/gcc/tree-ssa-strlen.c b/gcc/tree-ssa-strlen.c
index c6f74051607..8912a113de9 100644
--- a/gcc/tree-ssa-strlen.c
+++ b/gcc/tree-ssa-strlen.c
@@ -5491,6 +5491,8 @@ public:
     m_cleanup_cfg (false)
   { }
 
+  ~strlen_dom_walker ();
+
   virtual edge before_dom_children (basic_block);
   virtual void after_dom_children (basic_block);
 
@@ -5508,6 +5510,13 @@ public:
   bool m_cleanup_cfg;
 };
 
+/* Release pointer_query cache.  */
+
+strlen_dom_walker::~strlen_dom_walker ()
+{
+  ptr_qry.flush_cache ();
+}
+
 /* Callback for walk_dominator_tree.  Attempt to optimize various
    string ops by remembering string lengths pointed by pointer SSA_NAMEs.  */