diff --git a/src/ds/ds_set.c b/src/ds/ds_set.c
index 3ab7b9a..e36b510 100644
--- a/src/ds/ds_set.c
+++ b/src/ds/ds_set.c
@@ -80,6 +80,7 @@ static inline void add_array_to_set(ds_set_t *set, HashTable *array)
 {
     zval *value;
     ZEND_HASH_FOREACH_VAL(array, value) {
+        ZVAL_DEREF(value);
         ds_set_add(set, value);
     }
     ZEND_HASH_FOREACH_END();