diff --git a/libstdc++-v3/include/debug/helper_functions.h b/libstdc++-v3/include/debug/helper_functions.h
index dccf8e9e5e6375e75fe847c14cb4955183d2d7ed..052b36b484c4f6971a6fd000f5557fc8a006178e 100644
--- a/libstdc++-v3/include/debug/helper_functions.h
+++ b/libstdc++-v3/include/debug/helper_functions.h
@@ -111,12 +111,19 @@ namespace __gnu_debug
     _GLIBCXX_CONSTEXPR
     inline typename _Distance_traits<_Iterator>::__type
     __get_distance(_Iterator __lhs, _Iterator __rhs)
-    { return __get_distance(__lhs, __rhs, std::__iterator_category(__lhs)); }
+    {
+      return __gnu_debug::__get_distance(__lhs, __rhs,
+					 std::__iterator_category(__lhs));
+    }
 
   // An arbitrary iterator pointer is not singular.
   inline bool
   __check_singular_aux(const void*) { return false; }
 
+  // Defined in <debug/safe_base.h>
+  bool
+  __check_singular_aux(const class _Safe_iterator_base*);
+
   // We may have an iterator that derives from _Safe_iterator_base but isn't
   // a _Safe_iterator.
   template<typename _Iterator>
@@ -125,7 +132,7 @@ namespace __gnu_debug
     __check_singular(_Iterator const& __x)
     {
       return ! std::__is_constant_evaluated()
-	       && __check_singular_aux(std::__addressof(__x));
+	       && __gnu_debug::__check_singular_aux(std::__addressof(__x));
     }
 
   /** Non-NULL pointers are nonsingular. */
@@ -163,7 +170,8 @@ namespace __gnu_debug
 		      std::input_iterator_tag)
     {
       return __first == __last
-	|| (!__check_singular(__first) && !__check_singular(__last));
+	|| (!__gnu_debug::__check_singular(__first)
+	      && !__gnu_debug::__check_singular(__last));
     }
 
   template<typename _InputIterator>
@@ -172,8 +180,8 @@ namespace __gnu_debug
     __valid_range_aux(_InputIterator __first, _InputIterator __last,
 		      std::random_access_iterator_tag)
     {
-      return
-	__valid_range_aux(__first, __last, std::input_iterator_tag())
+      return __gnu_debug::__valid_range_aux(__first, __last,
+					    std::input_iterator_tag())
 	&& __first <= __last;
     }
 
@@ -186,8 +194,8 @@ namespace __gnu_debug
     __valid_range_aux(_InputIterator __first, _InputIterator __last,
 		      std::__false_type)
     {
-      return __valid_range_aux(__first, __last,
-			       std::__iterator_category(__first));
+      return __gnu_debug::__valid_range_aux(__first, __last,
+					    std::__iterator_category(__first));
     }
 
   template<typename _InputIterator>
@@ -197,10 +205,11 @@ namespace __gnu_debug
 		      typename _Distance_traits<_InputIterator>::__type& __dist,
 		      std::__false_type)
     {
-      if (!__valid_range_aux(__first, __last, std::input_iterator_tag()))
+      if (!__gnu_debug::__valid_range_aux(__first, __last,
+					  std::input_iterator_tag()))
 	return false;
 
-      __dist = __get_distance(__first, __last);
+      __dist = __gnu_debug::__get_distance(__first, __last);
       switch (__dist.second)
 	{
 	case __dp_none:
@@ -231,7 +240,8 @@ namespace __gnu_debug
 		  typename _Distance_traits<_InputIterator>::__type& __dist)
     {
       typedef typename std::__is_integer<_InputIterator>::__type _Integral;
-      return __valid_range_aux(__first, __last, __dist, _Integral());
+      return __gnu_debug::__valid_range_aux(__first, __last, __dist,
+					    _Integral());
     }
 
   template<typename _Iterator, typename _Sequence, typename _Category>
@@ -254,7 +264,7 @@ namespace __gnu_debug
     __valid_range(_InputIterator __first, _InputIterator __last)
     {
       typedef typename std::__is_integer<_InputIterator>::__type _Integral;
-      return __valid_range_aux(__first, __last, _Integral());
+      return __gnu_debug::__valid_range_aux(__first, __last, _Integral());
     }
 
   template<typename _Iterator, typename _Sequence, typename _Category>