diff --git a/parallel_hashmap/phmap.h b/parallel_hashmap/phmap.h
index 8ae2ca6..dca52bf 100644
--- a/parallel_hashmap/phmap.h
+++ b/parallel_hashmap/phmap.h
@@ -3409,7 +3409,7 @@ public:
     }
 
     template <class K = key_type, class F>
-    bool if_contains(const key_arg<K>& key, F&& f) {
+    bool if_contains(const key_arg<K>& key, F&& f) const {
         typename Lockable::SharedLock m;
         auto it = const_cast<parallel_hash_map*>(this)->find(key, hash(key), m);
         if (it == this->end())