diff --git a/include/boost/container/flat_map.hpp b/include/boost/container/flat_map.hpp
index 366f073..3a21ea9 100644
--- a/include/boost/container/flat_map.hpp
+++ b/include/boost/container/flat_map.hpp
@@ -1465,7 +1465,7 @@ class flat_map
    //! <b>Complexity</b>: Logarithmic.
    template<class K>
    BOOST_CONTAINER_FORCEINLINE std::pair<iterator,iterator> equal_range(const K& x)
-      {  return dtl::force_copy<std::pair<iterator,iterator> >(m_flat_tree.lower_bound_range(x)); }
+      {  return dtl::force_copy<std::pair<iterator,iterator> >(m_flat_tree.equal_range(x)); }
 
    //! <b>Requires</b>: This overload is available only if
    //! key_compare::is_transparent exists.
@@ -1475,7 +1475,7 @@ class flat_map
    //! <b>Complexity</b>: Logarithmic.
    template<class K>
    BOOST_CONTAINER_FORCEINLINE std::pair<const_iterator, const_iterator> equal_range(const K& x) const
-      {  return dtl::force_copy<std::pair<const_iterator,const_iterator> >(m_flat_tree.lower_bound_range(x)); }
+      {  return dtl::force_copy<std::pair<const_iterator,const_iterator> >(m_flat_tree.equal_range(x)); }
 
    //! <b>Effects</b>: Extracts the internal sequence container.
    //!
diff --git a/include/boost/container/flat_set.hpp b/include/boost/container/flat_set.hpp
index 5dae0f9..2b69e1a 100644
--- a/include/boost/container/flat_set.hpp
+++ b/include/boost/container/flat_set.hpp
@@ -1031,7 +1031,7 @@ class flat_set
    //! <b>Complexity</b>: Logarithmic
    template<typename K>
    std::pair<iterator,iterator> equal_range(const K& x)
-   {  return this->tree_t::lower_bound_range(x);  }
+   {  return this->tree_t::equal_range(x);  }
 
    //! <b>Requires</b>: This overload is available only if
    //! key_compare::is_transparent exists.
@@ -1041,7 +1041,7 @@ class flat_set
    //! <b>Complexity</b>: Logarithmic
    template<typename K>
    std::pair<const_iterator,const_iterator> equal_range(const K& x) const
-   {  return this->tree_t::lower_bound_range(x);  }
+   {  return this->tree_t::equal_range(x);  }
 
    #if defined(BOOST_CONTAINER_DOXYGEN_INVOKED)
 
diff --git a/test/flat_map_test.cpp b/test/flat_map_test.cpp
index 9595775..d01598b 100644
--- a/test/flat_map_test.cpp
+++ b/test/flat_map_test.cpp
@@ -25,6 +25,7 @@
 #include "../../intrusive/test/iterator_test.hpp"
 
 #include <map>
+#include <utility>
 
 
 using namespace boost::container;
@@ -560,6 +561,37 @@ bool test_heterogeneous_lookups()
    return true;
 }
 
+// An ordered sequence of std:pair is also ordered by std::pair::first.
+struct with_lookup_by_first
+{
+   typedef void is_transparent;
+   inline bool operator()(std::pair<int, int> a, std::pair<int, int> b) const
+   {
+      return a < b;
+   }
+   inline bool operator()(std::pair<int, int> a, int first) const
+   {
+      return a.first < first;
+   }
+   inline bool operator()(int first, std::pair<int, int> b) const
+   {
+      return first < b.first;
+   }
+};
+
+bool test_heterogeneous_lookup_by_partial_key()
+{
+   typedef flat_map<std::pair<int, int>,int, with_lookup_by_first> map_t;
+
+   map_t map1;
+   map1[std::pair<int, int>(0, 1)] = 3;
+   map1[std::pair<int, int>(0, 2)] = 3;
+
+   std::pair<map_t::iterator, map_t::iterator> const first_0_range = map1.equal_range(0);
+
+   return 2 == first_0_range.second - first_0_range.first;
+}
+
 }}}   //namespace boost::container::test
 
 int main()
@@ -620,6 +652,9 @@ int main()
    if (!test_heterogeneous_lookups())
       return 1;
 
+   if (!test_heterogeneous_lookup_by_partial_key())
+      return 1;
+
    ////////////////////////////////////
    //    Testing allocator implementations
    ////////////////////////////////////
diff --git a/test/flat_set_test.cpp b/test/flat_set_test.cpp
index 0ffb839..693305f 100644
--- a/test/flat_set_test.cpp
+++ b/test/flat_set_test.cpp
@@ -12,6 +12,7 @@
 
 #include <iostream>
 #include <set>
+#include <utility>
 #include <vector>
 
 #include <boost/container/flat_set.hpp>
@@ -576,6 +577,37 @@ bool test_heterogeneous_lookups()
    return true;
 }
 
+// An ordered sequence of std:pair is also ordered by std::pair::first.
+struct with_lookup_by_first
+{
+   typedef void is_transparent;
+   inline bool operator()(std::pair<int, int> a, std::pair<int, int> b) const
+   {
+      return a < b;
+   }
+   inline bool operator()(std::pair<int, int> a, int first) const
+   {
+      return a.first < first;
+   }
+   inline bool operator()(int first, std::pair<int, int> b) const
+   {
+      return first < b.first;
+   }
+};
+
+bool test_heterogeneous_lookup_by_partial_key()
+{
+   typedef flat_set<std::pair<int, int>, with_lookup_by_first> set_t;
+
+   set_t set1;
+   set1.insert(std::pair<int, int>(0, 1));
+   set1.insert(std::pair<int, int>(0, 2));
+
+   std::pair<set_t::iterator, set_t::iterator> const first_0_range = set1.equal_range(0);
+
+   return 2 == first_0_range.second - first_0_range.first;
+}
+
 }}}
 
 template<class VoidAllocatorOrContainer>
@@ -717,6 +749,10 @@ int main()
       return 1;
    }
 
+   if(!test_heterogeneous_lookup_by_partial_key()){
+      return 1;
+   }
+
    ////////////////////////////////////
    //    Testing allocator implementations
    ////////////////////////////////////