diff --git a/include/nlohmann/detail/meta/type_traits.hpp b/include/nlohmann/detail/meta/type_traits.hpp
index dc20cc08b..f25afd2ce 100644
--- a/include/nlohmann/detail/meta/type_traits.hpp
+++ b/include/nlohmann/detail/meta/type_traits.hpp
@@ -399,11 +399,13 @@ struct is_constructible_tuple<T1, std::tuple<Args...>> : conjunction<std::is_con
 template<typename BasicJsonType, typename KeyType>
 struct is_key_type
 {
-    static constexpr bool value =
+    static constexpr bool value = (
 #if defined(JSON_HAS_CPP_17)
-        std::is_same<typename std::decay<KeyType>::type, std::string_view>::value ||
+                                      std::is_same<typename std::decay<KeyType>::type, std::string_view>::value ||
 #endif
-        std::is_convertible<KeyType, typename BasicJsonType::object_t::key_type>::value;
+                                      std::is_convertible<KeyType, typename BasicJsonType::object_t::key_type>::value)
+                                  && !std::is_same<KeyType, typename BasicJsonType::iterator>::value
+                                  && !std::is_same<KeyType, typename BasicJsonType::const_iterator>::value;
 };
 
 }  // namespace detail
diff --git a/single_include/nlohmann/json.hpp b/single_include/nlohmann/json.hpp
index c7f9e2b46..fd5a62c42 100644
--- a/single_include/nlohmann/json.hpp
+++ b/single_include/nlohmann/json.hpp
@@ -3776,11 +3776,13 @@ struct is_constructible_tuple<T1, std::tuple<Args...>> : conjunction<std::is_con
 template<typename BasicJsonType, typename KeyType>
 struct is_key_type
 {
-    static constexpr bool value =
+    static constexpr bool value = (
 #if defined(JSON_HAS_CPP_17)
-        std::is_same<typename std::decay<KeyType>::type, std::string_view>::value ||
+                                      std::is_same<typename std::decay<KeyType>::type, std::string_view>::value ||
 #endif
-        std::is_convertible<KeyType, typename BasicJsonType::object_t::key_type>::value;
+                                      std::is_convertible<KeyType, typename BasicJsonType::object_t::key_type>::value)
+                                  && !std::is_same<KeyType, typename BasicJsonType::iterator>::value
+                                  && !std::is_same<KeyType, typename BasicJsonType::const_iterator>::value;
 };
 
 }  // namespace detail