diff --git a/include/boost/archive/basic_archive.hpp b/include/boost/archive/basic_archive.hpp
index ce7ac99a..20acc107 100644
--- a/include/boost/archive/basic_archive.hpp
+++ b/include/boost/archive/basic_archive.hpp
@@ -127,11 +127,11 @@ public:
     }
 
     // used for text output
-    operator int () const {
+    operator base_type () const {
         return t;
     }                
     // used for text input
-    operator int_least16_t &() {
+    operator base_type &() {
         return t;
     }                
     bool operator==(const class_id_type & rhs) const {
@@ -162,11 +162,11 @@ public:
         return *this;
     }
     // used for text output
-    operator uint_least32_t () const {
+    operator base_type () const {
         return t;
     }                
     // used for text input
-    operator uint_least32_t & () {
+    operator base_type & () {
         return t;
     }                
     bool operator==(const object_id_type & rhs) const {