diff --git a/doc/ref.xml b/doc/ref.xml
index da982b62..008e7c7c 100644
--- a/doc/ref.xml
+++ b/doc/ref.xml
@@ -181,7 +181,7 @@ file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
               <para>The copy constructor. Copies the contained elements, hash function, predicate, maximum load factor and allocator.</para>
             </description>
           </constructor>
-          <constructor>
+          <constructor specifiers="explicit">
             <parameter name="a">
               <paramtype>Allocator const&amp;</paramtype>
             </parameter>
@@ -928,7 +928,7 @@ file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
               <para>The copy constructor. Copies the contained elements, hash function, predicate, maximum load factor and allocator.</para>
             </description>
           </constructor>
-          <constructor>
+          <constructor specifiers="explicit">
             <parameter name="a">
               <paramtype>Allocator const&amp;</paramtype>
             </parameter>
@@ -1685,7 +1685,7 @@ file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
               <para>The copy constructor. Copies the contained elements, hash function, predicate, maximum load factor and allocator.</para>
             </description>
           </constructor>
-          <constructor>
+          <constructor specifiers="explicit">
             <parameter name="a">
               <paramtype>Allocator const&amp;</paramtype>
             </parameter>
@@ -2483,7 +2483,7 @@ file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
               <para>The copy constructor. Copies the contained elements, hash function, predicate, maximum load factor and allocator.</para>
             </description>
           </constructor>
-          <constructor>
+          <constructor specifiers="explicit">
             <parameter name="a">
               <paramtype>Allocator const&amp;</paramtype>
             </parameter>
@@ -3062,4 +3062,4 @@ file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
         </class>
       </namespace>
     </header>
-  </library-reference>
\ No newline at end of file
+  </library-reference>
diff --git a/include/boost/unordered_map.hpp b/include/boost/unordered_map.hpp
index 093c7697..5f711650 100644
--- a/include/boost/unordered_map.hpp
+++ b/include/boost/unordered_map.hpp
@@ -107,8 +107,7 @@ namespace boost
         {
         }
 
-        // TODO: Should this be explicit?
-        unordered_map(allocator_type const& a)
+        explicit unordered_map(allocator_type const& a)
             : base(boost::unordered_detail::default_initial_bucket_count,
                 hasher(), key_equal(), a)
         {
@@ -504,7 +503,7 @@ namespace boost
         {
         }
 
-        unordered_multimap(allocator_type const& a)
+        explicit unordered_multimap(allocator_type const& a)
             : base(boost::unordered_detail::default_initial_bucket_count,
                 hasher(), key_equal(), a)
         {
diff --git a/include/boost/unordered_set.hpp b/include/boost/unordered_set.hpp
index 1addae10..0f34c0fd 100644
--- a/include/boost/unordered_set.hpp
+++ b/include/boost/unordered_set.hpp
@@ -104,8 +104,7 @@ namespace boost
         {
         }
 
-        // TODO: Should this be explicit?
-        unordered_set(allocator_type const& a)
+        explicit unordered_set(allocator_type const& a)
             : base(boost::unordered_detail::default_initial_bucket_count,
                 hasher(), key_equal(), a)
         {
@@ -473,8 +472,7 @@ namespace boost
         {
         }
 
-        // TODO: Should this be explicit?
-        unordered_multiset(allocator_type const& a)
+        explicit unordered_multiset(allocator_type const& a)
             : base(boost::unordered_detail::default_initial_bucket_count,
                 hasher(), key_equal(), a)
         {