diff --git a/include/nlohmann/detail/iterators/iteration_proxy.hpp b/include/nlohmann/detail/iterators/iteration_proxy.hpp
index 3e181d5d9..1b47faeb3 100644
--- a/include/nlohmann/detail/iterators/iteration_proxy.hpp
+++ b/include/nlohmann/detail/iterators/iteration_proxy.hpp
@@ -39,7 +39,7 @@ template<typename IteratorType> class iteration_proxy_value
     /// a string representation of the array index
     mutable string_type array_index_str = "0";
     /// an empty string (to return a reference for primitive values)
-    const string_type empty_str;
+    const string_type empty_str{};
 
   public:
     explicit iteration_proxy_value(IteratorType it) noexcept : anchor(it) {}
diff --git a/single_include/nlohmann/json.hpp b/single_include/nlohmann/json.hpp
index 03579b189..30dd96f43 100644
--- a/single_include/nlohmann/json.hpp
+++ b/single_include/nlohmann/json.hpp
@@ -3944,7 +3944,7 @@ template<typename IteratorType> class iteration_proxy_value
     /// a string representation of the array index
     mutable string_type array_index_str = "0";
     /// an empty string (to return a reference for primitive values)
-    const string_type empty_str;
+    const string_type empty_str{};
 
   public:
     explicit iteration_proxy_value(IteratorType it) noexcept : anchor(it) {}