diff --git a/src/json.hpp b/src/json.hpp
index f2e02628..8883acd9 100644
--- a/src/json.hpp
+++ b/src/json.hpp
@@ -6159,6 +6159,10 @@ class basic_json
     */
     class serializer
     {
+      private:
+        serializer(const serializer&) = delete;
+        serializer& operator=(const serializer&) = delete;
+
       public:
         /*!
         @param[in] s  output stream to serialize to
diff --git a/src/json.hpp.re2c b/src/json.hpp.re2c
index 3a53f16c..6e90e6b8 100644
--- a/src/json.hpp.re2c
+++ b/src/json.hpp.re2c
@@ -6159,6 +6159,10 @@ class basic_json
     */
     class serializer
     {
+      private:
+        serializer(const serializer&) = delete;
+        serializer& operator=(const serializer&) = delete;
+
       public:
         /*!
         @param[in] s  output stream to serialize to