diff --git a/src/core/include/mp-units/ext/algorithm.h b/src/core/include/mp-units/ext/algorithm.h
index 3aa460b8..4e9f77c0 100644
--- a/src/core/include/mp-units/ext/algorithm.h
+++ b/src/core/include/mp-units/ext/algorithm.h
@@ -131,4 +131,18 @@ constexpr OutputIt copy(InputIt first, InputIt last, OutputIt d_first)
   return d_first;
 }
 
+template<class ForwardIt1, class ForwardIt2>
+constexpr void iter_swap(ForwardIt1 a, ForwardIt2 b)
+{
+  using std::swap;
+  swap(*a, *b);
+}
+
+template<class ForwardIt1, class ForwardIt2>
+constexpr ForwardIt2 swap_ranges(ForwardIt1 first1, ForwardIt1 last1, ForwardIt2 first2)
+{
+  for (; first1 != last1; ++first1, ++first2) iter_swap(first1, first2);
+  return first2;
+}
+
 }  // namespace mp_units::detail
diff --git a/src/core/include/mp-units/ext/fixed_string.h b/src/core/include/mp-units/ext/fixed_string.h
index 05c12f4e..1b1d13cf 100644
--- a/src/core/include/mp-units/ext/fixed_string.h
+++ b/src/core/include/mp-units/ext/fixed_string.h
@@ -141,7 +141,7 @@ public:
   }
 
   // modifiers
-  constexpr void swap(basic_fixed_string& s) noexcept { std::swap_ranges(begin(), end(), s.begin()); }
+  constexpr void swap(basic_fixed_string& s) noexcept { swap_ranges(begin(), end(), s.begin()); }
 
   // string operations
   [[nodiscard]] constexpr const_pointer c_str() const noexcept { return data(); }