diff --git a/include/boost/iterator/detail/facade_iterator_category.hpp b/include/boost/iterator/detail/facade_iterator_category.hpp
index 2d808da..1c540ee 100644
--- a/include/boost/iterator/detail/facade_iterator_category.hpp
+++ b/include/boost/iterator/detail/facade_iterator_category.hpp
@@ -22,21 +22,6 @@ namespace boost {
 namespace iterators {
 namespace detail {
 
-struct input_output_iterator_tag :
-    public std::input_iterator_tag
-{
-    // Using inheritance for only input_iterator_tag helps to avoid
-    // ambiguities when a stdlib implementation dispatches on a
-    // function which is overloaded on both input_iterator_tag and
-    // output_iterator_tag, as STLPort does, in its __valid_range
-    // function.  I claim it's better to avoid the ambiguity in these
-    // cases.
-    operator std::output_iterator_tag() const
-    {
-        return std::output_iterator_tag();
-    }
-};
-
 #ifdef BOOST_ITERATOR_REF_CONSTNESS_KILLS_WRITABILITY
 
 template< typename T >
diff --git a/test/unit_tests.cpp b/test/unit_tests.cpp
index 76bbffb..0258e56 100644
--- a/test/unit_tests.cpp
+++ b/test/unit_tests.cpp
@@ -6,9 +6,25 @@
 
 #include "static_assert_same.hpp"
 
+#include <iterator>
 #include <type_traits>
 #include <boost/iterator/minimum_category.hpp>
 
+struct input_output_iterator_tag :
+    public std::input_iterator_tag
+{
+    // Using inheritance for only input_iterator_tag helps to avoid
+    // ambiguities when a stdlib implementation dispatches on a
+    // function which is overloaded on both input_iterator_tag and
+    // output_iterator_tag, as STLPort does, in its __valid_range
+    // function.  I claim it's better to avoid the ambiguity in these
+    // cases.
+    operator std::output_iterator_tag() const
+    {
+        return std::output_iterator_tag();
+    }
+};
+
 struct X { int a; };
 
 
@@ -43,7 +59,7 @@ void category_test()
         "std::input_iterator_tag is not expected to be convertible to input_output_iterator_tag.");
 
     static_assert(
-        !std::is_convertible<std::output_iterator_tag , input_output_iterator_tag>::value,
+        !std::is_convertible<std::output_iterator_tag, input_output_iterator_tag>::value,
         "std::output_iterator_tag is not expected to be convertible to input_output_iterator_tag.");
 
     static_assert(
@@ -65,31 +81,31 @@ void category_test()
 #endif
 
     int test = static_assert_min_cat<
-        std::input_iterator_tag,input_output_iterator_tag, std::input_iterator_tag
+        std::input_iterator_tag, input_output_iterator_tag, std::input_iterator_tag
     >::value;
 
     test = static_assert_min_cat<
-        input_output_iterator_tag,std::input_iterator_tag, std::input_iterator_tag
+        input_output_iterator_tag, std::input_iterator_tag, std::input_iterator_tag
     >::value;
 
 #if 0
     test = static_assert_min_cat<
-        input_output_iterator_tag,std::forward_iterator_tag, input_output_iterator_tag
+        input_output_iterator_tag, std::forward_iterator_tag, input_output_iterator_tag
     >::value;
 #endif
 
     test = static_assert_min_cat<
-        std::input_iterator_tag,std::forward_iterator_tag, std::input_iterator_tag
+        std::input_iterator_tag, std::forward_iterator_tag, std::input_iterator_tag
     >::value;
 
     test = static_assert_min_cat<
-        std::input_iterator_tag,std::random_access_iterator_tag, std::input_iterator_tag
+        std::input_iterator_tag, std::random_access_iterator_tag, std::input_iterator_tag
     >::value;
 
 #if 0  // This would be wrong: a random access iterator is not
        // neccessarily writable, as is an output iterator.
     test = static_assert_min_cat<
-        std::output_iterator_tag,std::random_access_iterator_tag, std::output_iterator_tag
+        std::output_iterator_tag, std::random_access_iterator_tag, std::output_iterator_tag
     >::value;
 #endif