diff --git a/include/xo/printjson/JsonPrinter.hpp b/include/xo/printjson/JsonPrinter.hpp
index c1b8b62a..2be405c0 100644
--- a/include/xo/printjson/JsonPrinter.hpp
+++ b/include/xo/printjson/JsonPrinter.hpp
@@ -12,87 +12,87 @@
 #include <iostream>
 
 namespace xo {
-  namespace json {
-    class PrintJson;
+    namespace json {
+        class PrintJson;
 
-    class JsonPrinter {
-    public:
-      using Reflect = xo::reflect::Reflect;
-      using TaggedPtr = xo::reflect::TaggedPtr;
-      using TypeDescr = xo::reflect::TypeDescr;
-      using TypeId = xo::reflect::TypeId;
+        class JsonPrinter {
+        public:
+            using Reflect = xo::reflect::Reflect;
+            using TaggedPtr = xo::reflect::TaggedPtr;
+            using TypeDescr = xo::reflect::TypeDescr;
+            using TypeId = xo::reflect::TypeId;
 
-    public:
-      JsonPrinter(PrintJson const * pjson) : pjson_{pjson} {}
-      virtual ~JsonPrinter() = default;
+        public:
+            JsonPrinter(PrintJson const * pjson) : pjson_{pjson} {}
+            virtual ~JsonPrinter() = default;
 
-      PrintJson const * pjson() const { return pjson_; }
+            PrintJson const * pjson() const { return pjson_; }
 
-      /* print tagged pointer in json format */
-      virtual void print_json(TaggedPtr tp,
-                  std::ostream * p_os) const = 0;
+            /* print tagged pointer in json format */
+            virtual void print_json(TaggedPtr tp,
+                                    std::ostream * p_os) const = 0;
 
-      void report_internal_type_consistency_error(TypeDescr td1,
-                          TypeDescr td2,
-                          std::ostream * p_os) const;
+            void report_internal_type_consistency_error(TypeDescr td1,
+                                                        TypeDescr td2,
+                                                        std::ostream * p_os) const;
 
-      /* convenience method for derived printers.
-       * retrieves contents of tp as a T*,  complains to *p_os if that fails.
-       *
-       * (Failure would occur if printer for type T was instead installed
-       *  for some unrelated type U)
-       */
-      template<typename T>
-      T * check_recover_native(TaggedPtr tp, std::ostream * p_os) const {
-    T * x = tp.recover_native<T>();
+            /* convenience method for derived printers.
+             * retrieves contents of tp as a T*,  complains to *p_os if that fails.
+             *
+             * (Failure would occur if printer for type T was instead installed
+             *  for some unrelated type U)
+             */
+            template<typename T>
+            T * check_recover_native(TaggedPtr tp, std::ostream * p_os) const {
+                T * x = tp.recover_native<T>();
 
-    if (!x) {
-      this->report_internal_type_consistency_error(Reflect::require<T>(),
-                               tp.td(),
-                               p_os);
-    }
+                if (!x) {
+                    this->report_internal_type_consistency_error(Reflect::require<T>(),
+                                                                 tp.td(),
+                                                                 p_os);
+                }
 
-    return x;
-      } /*check_recover_native*/
+                return x;
+            } /*check_recover_native*/
 
-      void assign_pjson(PrintJson const * pjson) {
-    assert(this->pjson_ == nullptr || this->pjson_ == pjson);
-    this->pjson_ = pjson;
-      } /*assign_pjson*/
+            void assign_pjson(PrintJson const * pjson) {
+                assert(this->pjson_ == nullptr || this->pjson_ == pjson);
+                this->pjson_ = pjson;
+            } /*assign_pjson*/
 
-    private:
-      /* a json printers is installed into one PrintJson instance;
-       * capture address of that instance at install time
-       */
-      PrintJson const * pjson_ = nullptr;
-    }; /*JsonPrinter*/
+        private:
+            /* a json printers is installed into one PrintJson instance;
+             * capture address of that instance at install time
+             */
+            PrintJson const * pjson_ = nullptr;
+        }; /*JsonPrinter*/
 
-    /* AsStringJsonPrinter<T>
-     * prints a T-instance by using operator<< and surrounding in quotes.
-     *
-     * e.g:
-     *   T & x = ..;
-     *   std::ostream * p_os = ..;
-     *
-     *   *p_os << "\"" << x << "\""
-     *
-     */
-    template<typename T>
-    class AsStringJsonPrinter : public JsonPrinter {
-    public:
-      AsStringJsonPrinter(PrintJson const * pjson) : JsonPrinter(pjson) {}
+        /* AsStringJsonPrinter<T>
+         * prints a T-instance by using operator<< and surrounding in quotes.
+         *
+         * e.g:
+         *   T & x = ..;
+         *   std::ostream * p_os = ..;
+         *
+         *   *p_os << "\"" << x << "\""
+         *
+         */
+        template<typename T>
+        class AsStringJsonPrinter : public JsonPrinter {
+        public:
+            AsStringJsonPrinter(PrintJson const * pjson) : JsonPrinter(pjson) {}
 
-      virtual void print_json(TaggedPtr tp,
-                  std::ostream * p_os) const override
-      {
-    T * x = this->check_recover_native<T>(tp, p_os);
+            virtual void print_json(TaggedPtr tp,
+                                    std::ostream * p_os) const override
+                {
+                    T * x = this->check_recover_native<T>(tp, p_os);
 
-    if(x) {
-      *p_os << "\"" << *x << "\"";
-    }
-      } /*print_json*/
-    }; /*AsStringJsonPrinter*/
-  } /*namespace json*/
+                    if(x) {
+                        *p_os << "\"" << *x << "\"";
+                    }
+                } /*print_json*/
+        }; /*AsStringJsonPrinter*/
+    } /*namespace json*/
 } /*namespace xo*/