diff --git a/casbin/model/policy_collection.cpp b/casbin/model/policy_collection.cpp
index 6f422e83..705e119e 100644
--- a/casbin/model/policy_collection.cpp
+++ b/casbin/model/policy_collection.cpp
@@ -17,6 +17,9 @@
 #include "casbin/model/policy_collection.hpp"
 
 #include <iostream>
+PoliciesValues::PoliciesValues()
+    : opt_base_vector(std::initializer_list<PolicyValues>{}), opt_base_hashset({}) {}
+
 PoliciesValues::PoliciesValues(PoliciesVector&& base_collection)
     : opt_base_vector(base_collection), opt_base_hashset({}) {}
 
diff --git a/include/casbin/model/policy_collection.hpp b/include/casbin/model/policy_collection.hpp
index 14050a6b..4762e2e7 100644
--- a/include/casbin/model/policy_collection.hpp
+++ b/include/casbin/model/policy_collection.hpp
@@ -45,7 +45,8 @@ using PoliciesHashset = std::unordered_set<PolicyValues>;
     PoliciesValues(PoliciesVector&& base_collection);
     PoliciesValues(PoliciesHashset&& base_collection);
 public:
-    PoliciesValues(const std::initializer_list<PolicyValues>& list={});
+    PoliciesValues();
+    PoliciesValues(const std::initializer_list<PolicyValues>& list);
     PoliciesValues(size_t capacity);
     static PoliciesValues createWithVector(const std::initializer_list<PolicyValues>& list={});
     static PoliciesValues createWithHashset(const std::initializer_list<PolicyValues>& list={});