diff --git a/include/boost/algorithm/string/find_iterator.hpp b/include/boost/algorithm/string/find_iterator.hpp
index 7b3f356..21bf748 100644
--- a/include/boost/algorithm/string/find_iterator.hpp
+++ b/include/boost/algorithm/string/find_iterator.hpp
@@ -44,7 +44,7 @@ namespace boost {
         {
         private:
             // facade support
-            friend class iterator_core_access;
+            friend class ::boost::iterator_core_access;
 
             // base type
             typedef iterator_facade<
@@ -189,7 +189,7 @@ namespace boost {
         {
         private:
             // facade support
-            friend class iterator_core_access;
+            friend class ::boost::iterator_core_access;
 
             // base type
             typedef iterator_facade<